In the ensuing years, the number of students attending the school grew and in 1936, it was decided that YIS should open a boarding facility on the Principal’s residence to give more scope to this increasing enrolment. By March 1937, the number of students had reached 102 compared to 52 the year before. Twelve teachers were employed at the time. The Yokohama Country and Athletic Club in the same year agreed to the school using its field on Wednesday afternoons for cricket and football (soccer). By 1939 YIS had grown to 110 students spanning 21 nationalities. Two years later, due to the pressures of war, constraints were being imposed on the school by the Japanese Government and by December of that year, YIS had closed. Soon after, the site became a refugee centre for German nationals, and then later an air defense training school. Unfortunately, on May 29, 1945, the school buildings were swept away by an air raid fire leaving only the concrete structures intact.
Under the act of the ‘Restoration of the United Nations Nationality Property in Japan’, in November 1951, repossession of the land that housed YIS was formally completed. With active support of foreign businesses and an indemnity payment received from the Japanese government, a new building was erected on the original site and the school was reopened on September 15, 1955 with an enrolment of 8 children.
During subsequent years, there was rapid enrolment growth and on March 9, 1958, over 150 foreigners and families of five nationalities attended the opening of a second building. With a third building being added in 1962 (known as ‘the Middle Building’), it gave more room for growth and by 1967, the enolment figure had reached 320 students. The ‘Main Building’ was added in 1969 and in the same year, the school became registered as a ‘School Juridical Person’, (Gakko Hojin).
The first cohort group of Grade 9 students began classes in the fall of the same year and this group of nine students became the first graduates of the school, the ‘Class of 1973’. In 1986, YIS began its first class for the International Baccalaureate Diploma Programme (IBDP), dispensing with the British ‘A’ Levels which were, up to that point, offered in the last two years of high school. The school became fully accredited in 1991 by the European Council of International Schools (ECIS) and the New England Association of Schools and Colleges (NEASC). Mid 1990’s, the school introduced the IGCSE (the International General Certificate in Secondary Education) in Grades 9 and 10, replacing the GCE’s (General Certificate in Education).
1999 was a year of celebration for the school – its 75th anniversary. A week of celebrations and events attended by dignitaries, former heads, parents, alumni, and the school community at large was organized, culminating in a huge party at the Pan Pacific Hotel in Yokohama with many ambassadors as guests of honour. In the same year the school founded the Schools Building Schools programme (SBS), a project involving the raising of funds to build schools in less fortunate countries around the world.
In 2000, YIS became the first school in Japan to offer the Reggio Emilia programme for the early learners, and a year later became the first school in Japan authorized to offer the Primary Years Programme of the IBO, the International Baccalaureate Organisation. By 2003, the school’s structure included the Early Learning Centre, (ages 3-5), an Elementary School (K-5), a Middle School, (Grades 6-8) and a High School, (Grades 9-12).
Presently, with an enrolment of around 650 students representing over 45 nationalities and faculty and staff numbering almost 100 people spanning over 15 nationalities, supported by various programmes and a culture rich in diversity, YIS strives to offer its internationally minded students a well-balanced international education. The school's curricula, its student-centered approach to teaching and learning, and its mission, values and aims, all add in promoting the continuum for learning in an international context. Aspiring to instill the qualities embodied in the IB Learner Profile, YIS helps students to become better communicators, become more open-minded, principled, inquirers, knowledgeable, thinkers, caring citizens, risk-takers, balanced and reflective.
YIS, with a long history, played an important role in the 150th celebrations of the Port of Yokohama held in 2009, and in turn, it is without doubt that the city will join us in commemorating the 100th anniversary of the school in 2024.