四

one metropolis (Tokyo), one "circuit" (Hokkaido), two urban prefectures (Osaka and Kyoto) and 43 prefectures proper; prefectures of Japan

Idiomatic expression

The world is at peace

Organization name

Shikoku University

enjoying food, drink and entertainment in a small room

carbon-14 dating; radiocarbon dating

the common run of men; the average Joe; good-for-nothing (person)

people in the whole world being all brothers; universal brotherhood

tesseract

士 represents November as it can be decomposed into 十一 (11)

nishimuku samurai (mnemonic for remembering the months with fewer than 31 days)

24 Hours of Le Mans; Le Mans 24-Hour Race

Twenty-Four Histories; authoritative collection of twenty-four Chinese historical books

schools of the upper quartile; highly ranked schools

Linguistics; じ,ぢ,ず,づ

yotsugana; the four kana (ji, di, zu, du)

four-letter word (vulgar English term, e.g. fuck)

the four tools of writing (brush, ink, inkstone and paper)

Russian tortoise (Agrionemys horsfieldii); Horsfield's tortoise; Central Asian tortoise; steppe tortoise; four-toed tortoise

wooden plane with a convex base curved both along the direction of cutting and across the blade

silicon tetrachloride (SiCl4)

Proverb

every person has their eccentricities

six-three-three-four system of education (six years of elementary school, three years each of junior and senior high school and four years of university)

third quarter (of the year)

first quarter (of the year)

second quarter (of the year)

fourth quarter (of the year)