Seisen admits boys, but only in kindergarten. The school's own answer to the question is exactly that: boys are accepted in the kindergarten program, which runs co-educationally from age two to six, and from Grade 1 the school is all girls. For a family with a son and a daughter that single fact decides how the next few years look, since the son leaves at six while the daughter stays for another twelve years. Many boys move to St. Mary's International School, the boys' Catholic school a short distance away in Setagaya, and the two schools run joint plays, musicals, Model United Nations, and a combined swim team.
The second thing that distinguishes Seisen is the depth of its IB. It has run the Diploma since 1986, added the Primary Years Programme in 2007 and the Middle Years Programme in 2020, and describes itself as the first all-girls IB continuum school in Japan. That means a girl can follow the IB from kindergarten to Grade 12 without changing framework, which no other school in this guide offers alongside a single-sex setting, and the Diploma results bear it out: an average of 35 in 2025 against a worldwide mean of 30.58.
Families come to Seisen wanting a girls' school, a Catholic environment, or a serious IB, and often all three. The practical questions we hear are about the shape of a family rather than the school: what happens to a son at six, whether a daughter arriving in the upper years can still take the Diploma, and how a bicultural child's Japanese will develop. That last one has a better answer here than at most schools, since Seisen offers Japanese as a first language at Diploma level rather than only as a foreign one.
We teach families remotely across roughly eight countries, and we work with families in Japan, though our Japan experience to date is in Kansai rather than Tokyo. We are not a school, we have no affiliation with Seisen and no referral arrangement with any school in this guide. What we help with is the English and mathematics the school assesses at entry, since every applicant from Grade 1 upward sits both, and the writing and analysis a Diploma of six subjects, an extended essay, and theory of knowledge demands. For a family from Taiwan or Hong Kong, note that Seisen teaches no Chinese.
The orienting facts, each drawn from the school's own materials and the IB's own directory, checked in September 2026. Figures are the school's own, in Japanese yen, and are not converted.
Seisen is operated by the Seisen Jogakuin Incorporated Educational Institution, a non-profit school corporation under the Handmaids of the Sacred Heart of Jesus, which runs nine schools in Japan of which Seisen International is the only English-medium one. It is accredited jointly by the Council of International Schools and the New England Association of Schools and Colleges, re-accredited in 2022 with the next evaluation in 2027, and is an authorized IB World School for all three programmes. It is not an Article 1 school under Japanese law, a point the school states itself. And it publishes its fees in full, in yen, which is why this guide can carry them.
Seisen publishes a full fee schedule. Fees are annual, and only tuition and the bus may be paid in two instalments, the first by mid-June and the second in January. The tables below are the school's own figures, in yen, and this guide does not convert them.
A new family pays ¥1,000,000 in one-time fees before tuition: a registration fee of ¥300,000 and a land and building development fee of ¥700,000, the second of which becomes non-refundable once a child attends any part of the year. A building maintenance fee of ¥150,000 applies annually. The school offers no scholarships, and its financial assistance is limited to families already enrolled who hit temporary difficulty, so a family should treat the published figures as what it will pay.
Annual. Excludes the ¥150,000 annual building maintenance fee.
| Grade band | Per year | With building fee |
|---|---|---|
| Kindergarten, half day | ¥1,500,000 | ¥1,650,000 |
| Kindergarten, full day | ¥2,500,000 | ¥2,650,000 |
| Grades 1 to 5 | ¥2,650,000 | ¥2,800,000 |
| Grades 6 to 12 | ¥2,700,000 | ¥2,850,000 |
Source: the school's own tuition and fees page, 2026 to 2027 schedule. Checked September 2026. The school corrected the half-day kindergarten figure on its own page, and this guide carries the corrected amount.
| Item | Amount | Applies to |
|---|---|---|
| Application fee | ¥30,000 | Non-refundable. An older page still says ¥20,000, so confirm when applying |
| Registration fee | ¥300,000 | New students, one time, non-refundable |
| Land and building development fee | ¥700,000 | New students, one time. Non-refundable once a child attends |
| Building maintenance | ¥150,000 | Annual, non-refundable |
| School bus | ¥310,000 one way, ¥420,000 both ways | Per year, eleven routes across central Tokyo |
| IB examinations | ¥20,000 per subject | In the Diploma years |
| Devices, graduation | Charged separately | An iPad from Grade 3, and ¥30,000 at graduation in Grade 12 |
| Scholarships, sibling discount | None published | No scholarships. Assistance only for enrolled families in difficulty |
For a new girl entering Grade 6 in 2026 to 2027, tuition of ¥2,700,000 plus the building maintenance fee of ¥150,000 and the one-time fees of ¥1,030,000 comes to ¥3,880,000 before the bus and devices. Adding a return bus place brings it to ¥4,300,000. Later years fall back to ¥2,850,000. These totals are Harland's arithmetic on the school's own figures, labelled as such.
| Grades served | Kindergarten from age two, co-educational, then Grades 1 to 12 for girls only. Kindergarten age cut-off 1 September |
|---|---|
| Enrollment | About 700 across the school, more than 40 nationalities, with 196 in the high school, per the school's 2025 to 2026 profile |
| Curriculum | Primary Years Programme in Grades 1 to 5, Middle Years Programme in Grades 6 to 10, and the Diploma in Grades 11 and 12. Montessori and Primary Years in kindergarten |
| IB authorisation | Diploma from 3 January 1986, Primary Years from 19 December 2007, Middle Years from 7 July 2020, per the IB's own directory |
| Senior pathways | Three, all requiring a two-year commitment: the school diploma with the full IB Diploma, with IB courses, or alone. All require the service requirement |
| Results 2025 | 43 Diploma candidates, 97.7 percent pass, average 35, eight scores of 40 or above. Mean SAT total 1174 for the class of 2025 |
| Destinations 2025 | Japan and Asia 37 percent, the United States and Canada 35 percent, the United Kingdom and Europe 18 percent, Australia and New Zealand 4 percent |
| Languages | Japanese and Spanish from Grade 1. At Diploma level Japanese as a first language and as a second, plus French and Spanish. No Chinese |
| Accreditation | Jointly accredited by the Council of International Schools and NEASC, re-accredited 2022, next evaluation 2027. Not an Article 1 school |
| Faculty | 99 teachers from 23 countries, the school's own figure. Head of School Colette Rogers since 2015 |
Where the school's own pages differ, as on the application fee, both figures are shown and this guide names the more recent. Items the school does not publish, including the application window and any rule on direct Grade 12 entry, are marked as such rather than filled from directory sites. All figures in yen, checked September 2026.
Seisen's structure is unusual, and worth understanding before a family reads anything else about it.
The school was founded in 1962 by the Handmaids of the Sacred Heart of Jesus, an order established in Madrid in 1877 by Rafaela María Porras y Ayllón, who was canonized in 1977. A first grade formed after the order moved a kindergarten from Yoyogi, the school settled on its Yoga campus in 1972, and the first class graduated in 1974. The name means pure spring in Japanese, the mascot is the phoenix, and the colours are maroon and navy.
The structure catches people out. Seisen International School is one of nine schools run by the Seisen Jogakuin Incorporated Educational Institution, and the other eight, including Seisen University in Shinagawa and the Seisen schools in Nagano, all teach in Japanese. So Seisen International is not a wholly separate institution from the Japanese-language Seisen schools a family may find while searching, it is the English-medium member of the same corporation, which sets policy, accounting, philosophy, and tuition across all nine. Its own mission is to educate future world citizens to become men and women for others and with others in the spirit of Jesus Christ, and its guiding principles include educating women for social and cultural transformation and siding with the poor.
Seisen runs all three IB programmes, which lets a girl stay inside one framework for her whole schooling, and gives her three routes through the final two years.
Kindergarten blends Montessori with the Primary Years Programme, which then runs through Grades 1 to 5, and the Middle Years Programme covers Grades 6 to 10, ending with the personal project in Grade 10. The Diploma occupies Grades 11 and 12. Because the school holds all three authorisations, a girl entering in kindergarten never changes framework, which is the practical benefit of a continuum and something no other school in this guide offers alongside a single-sex setting. There is no Advanced Placement here at all.
The senior years offer three pathways, and all of them require a two-year commitment. A girl can take the school's own high school diploma with the full IB Diploma, which means six subjects, theory of knowledge, a four-thousand-word extended essay, and the service requirement. She can take the school diploma with individual IB courses, which keeps the service requirement but drops the essay and theory of knowledge. Or she can take the school diploma alone, again with service. Subjects are chosen in the spring of Grade 10. On languages, Japanese and Spanish begin in Grade 1, and at Diploma level Japanese is offered both as a first language and as a second, so a bilingual girl keeps developing real literacy rather than repeating a beginner's course. French and Spanish complete the offering, and there is no Chinese, so a family arriving from Taiwan or Hong Kong should plan for that outside school.
Seisen publishes a school profile with three years of results, which makes it one of the more transparent schools in this guide on outcomes.
For 2025 the school reports 43 Diploma candidates, a pass rate of 97.7 percent, a school average of 35, and eight students scoring 40 or above. The two preceding years both averaged 34 with pass rates around 97.6 and 97.8 percent and similar candidate numbers, so the record is steady rather than a single strong year. Set against the International Baccalaureate's own published worldwide mean of 30.58 for the May 2025 session, an average of 35 is roughly four and a half points above the global figure. Mean SAT totals were 1174 for the class of 2025, 1204 for 2024, and 1276 for 2023.
On destinations, the school gives proportions rather than a list: for the class of 2025, 37 percent to Japan and Asia, 35 percent to the United States and Canada, 18 percent to the United Kingdom and Europe, and 4 percent to Australia and New Zealand. It states that all its graduates go on to higher education, and that classes from 2020 onward have attended more than a hundred institutions. When reading this, note that the school does not calculate a grade point average or rank its students, and it encourages girls to apply to no more than ten universities, which is a deliberate position on how the application year should feel.
Every applicant from Grade 1 to Grade 11 sits mathematics and English assessments, and kindergarten applicants are seen through an individual interview and observation, with a family interview with the relevant principal following in both cases. The application asks for the last two years of report cards, a photograph, the passport page, and recent standardized test scores where a family has them, though official transcripts are not needed at the point of applying. The school lists priority placement for siblings of current students, daughters of alumni, children of staff, returning students, and children from Catholic families, while stating that it welcomes applications irrespective of religion and that priority is not the same as acceptance.
On the practical side, the school does not publish an application window, a deadline, or how mid-year entry works, so a family should ask admissions directly rather than rely on what directory sites say. And because all three senior pathways require a two-year commitment, a girl aiming at the Diploma should be applying for Grade 11 rather than later. The school publishes no rule either way on entering directly into Grade 12, which is worth confirming in writing if that is your situation.
Harland is not a school and does not replace Seisen. We are a 1-on-1 tutoring academy, and we work with families in Japan and across roughly eight countries remotely, in the three places this school's structure creates real work for a family: the entry assessments, the years through the continuum, and the Diploma.
In kindergarten only. The school's own answer is direct: boys are accepted only in the kindergarten program, which runs co-educationally from age two to six. From Grade 1 onward Seisen is all girls, so a family with a son needs a plan for Grade 1, and many move to St. Mary's, the boys' Catholic school nearby in Setagaya.
All three. It has run the Diploma since 1986, added the Primary Years Programme in 2007 and the Middle Years Programme in 2020, and describes itself as the first all-girls IB continuum school in Japan. That is a fuller IB offering than St. Mary's, which runs the Diploma alone. Seisen offers no Advanced Placement.
For 2026 to 2027 the school publishes annual tuition of ¥1,500,000 for half-day kindergarten, ¥2,500,000 for full-day kindergarten, ¥2,650,000 for Grades 1 to 5, and ¥2,700,000 for Grades 6 to 12. A new family also pays a registration fee of ¥300,000 and a land and building development fee of ¥700,000, neither refundable, plus a ¥150,000 annual building maintenance fee. There are no scholarships.
Strong and consistently published. For 2025 the school reports 43 candidates, a pass rate of 97.7 percent, an average of 35 against a worldwide mean of 30.58, and eight students scoring 40 or above. The two preceding years averaged 34 with similar pass rates. The school does not calculate a grade point average or class rank.
Yes, with a caution the school states itself. It notes that Japanese law requires parents to send children to Article 1 schools through the nine compulsory years, that Seisen does not hold Article 1 status, and that Japanese parents must give full consideration to the legal implications before applying. It admits Japanese students who have spent at least two years in an English-medium school abroad, or who transfer from another international school and need minimal support.
Our Student Coordinator speaks with relocating families regularly, often before a posting is confirmed, and can help you think through how the co-ed kindergarten fits a family with sons and daughters, and how to prepare for assessments in English and mathematics. We work with families remotely. We start by listening.