K. International School Tokyo vs St. Mary's International School
🇯🇵 Tokyo · Side-by-side comparison on verifiable public data.
Neither K. International School Tokyo nor St. Mary's International School sits in a market with a public inspectorate, so both are assessed on verifiable accreditation, curriculum authorisation, and published data rather than an official quality rating. Curriculum is the core differentiator: K. International School Tokyo offers IB, British while St. Mary's International School offers IB, American — the choice should follow the family's target qualification system. Both are day schools with fees in the same market band — see the table below for the figures, and verify against each school's own published fees.
Key Facts
| K. International School Tokyo | St. Mary's International School | |
|---|---|---|
| Curriculum | IB / British | IB / American |
| Ages | 3–18 | 5–18 |
| Languages of instruction | English | English |
| Annual fees | JPY 2,850,000–3,020,000 | JPY 3,060,000–3,250,000 |
| Enrollment | 660 | 1,000 |
| Boarding | Day only | Day only |
| Accreditations | CIS, Edexcel | CIS, WASC |
Strengths
- ✓Outstanding, transparently published IB DP results (42.0/45 in 2025; five-year track record above 41)
- ✓Full CIS accreditation on a 5-year evaluation cycle — strong external quality assurance
- ✓Single-campus K1–G12 continuity (ages 3–18) — no transition between schools
- ✓Central, highly accessible Tokyo location (Shirakawa, Koto-ku); new 2024 main building
- ✓Established history (since 1997) with deep IB roots (IB World School since 2002)
- ✓Dual CIS + WASC accreditation — exceptional accreditation depth for a Japan-based school
- ✓Full K–12 continuity (ages ~5–18) on a single 9-acre campus, with IB DP capstone
- ✓70-year-old established institution with a clear, stable Catholic mission
- ✓Strongly international student body (~1,000 boys, ~60 nationalities)
- ✓Published, transparent IB DP subject offering (all six groups + TOK/CAS/EE)
Trade-offs
- !No EAL/language support for Grade 8 and above — students needing English help are explicitly not accepted
- !The IB continuum is incomplete in practice: MYP is no longer offered, and middle years run on Edexcel iLowerSecondary/IGCSE
- !High fees (~¥2.85M–3.02M annual tuition plus ¥700K capital and other one-time fees)
- !Third-party review sentiment is weak (small, unverified sample)
- !Enrollment/nationality figures differ between official site (~700/50+) and aggregators (660/45)
- !No published academic outcomes — IB average, pass rate and university destinations all not public
- !EAL/ESL support is not described anywhere public; English-language-learner provision is unverifiable
- !AP is sometimes assumed but is NOT publicly evidenced — only the IB DP is confirmed
- !Official tuition figures could not be confirmed on the school's own fees page (third-party only)
- !The school's Wikipedia entry references 2014 historical abuse allegations — a matter of public record families may wish to research independently
Best Fit For
- • Families seeking a top-tier, results-driven IB Diploma outcome
- • Children entering in the early years (K1–early primary) who can grow up in the system
- • English-fluent international and bilingual families based in central/east Tokyo
- • Families specifically seeking a single-sex, all-boys environment
- • Families wanting a Catholic / faith-based education within an international setting
- • Families prioritising accreditation rigour (CIS + WASC) as a quality signal
- • Long-stay expat or local families wanting K–12 continuity in one institution
University Placement
School-reported · not independently verified
School-reported: KIST publishes detailed IB DP results (42.0/45 average, 100% pass rate, 25% scoring 45 in 2025). A university-acceptance page exists but specific destination figures were not captured; treat placement claims as school-reported, unverified.
Not public. No university destinations, placement statistics, or matriculation lists are published, though the school maintains a University Counseling function.
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Frequently Asked Questions
Should I choose K. International School Tokyo or St. Mary's International School?
K. International School Tokyo is best for: Families seeking a top-tier, results-driven IB Diploma outcome. St. Mary's International School is best for: Families specifically seeking a single-sex, all-boys environment. The right choice depends on target curriculum, budget, and family priorities — the two are not linearly comparable.
How do fees compare between K. International School Tokyo and St. Mary's International School?
K. International School Tokyo: JPY 2,850,000–3,020,000. St. Mary's International School: JPY 3,060,000–3,250,000. Verify against each school's own published fees; some figures are sourced from third-party aggregators.
What curricula do K. International School Tokyo and St. Mary's International School offer?
K. International School Tokyo: IB, British. St. Mary's International School: IB, American.
Do K. International School Tokyo or St. Mary's International School offer boarding?
K. International School Tokyo: day school only. St. Mary's International School: day school only.
This comparison is BrightKey's independent assessment using verifiable public data only. University-placement figures are school-reported and not independently verified. BrightKey takes no payments from schools. Our method →