〜(日本) 式
～(にほん) しき · ～(nihon) shiki · JLPT N2 · noun
custom
日本式 = Japan + style: 式 shiki means the way or custom of doing it
式 (shiki) attaches to a noun to mean 'in that style or custom': 日本式 = Japanese-style, 西洋式 = Western-style. The kanji combines 工 (work) and 弋 (stake), suggesting a fixed pattern for doing work. The same 式 appears in 結婚式, a wedding ceremony.
日 — pictograph of the sun
日 is a pictograph of the sun, originally drawn as a circle with a dot or stroke inside representing the sun's substance. Over time the round shape was squared off into the modern rectangular form. It means 'sun' and by extension 'day'.
本 — tree 木 + mark at base
本 is a pictograph of a tree (木) with a stroke at its base, marking the roots. From this 'root' meaning it extended to 'origin,' 'source,' and 'foundation.' In modern usage it also serves as a measure word for bound objects like books.
式 — 工 (work) + 弋 (phonetic)
式 is a phono-semantic compound: 工 ('work, craft') gives the meaning of a tool, rule, or method, while 弋 supplies the sound. It originally referred to a standard pattern or model used in craftsmanship, then broadened to mean 'style, form, ceremony, or formula.'