sister city

ecology, mode of life of living creatures / way of life, the way people live

possibility, good chance / feasibility

possible / feasible

sex, gender / (grammar) gender

a sea, an ocean / a lake / (figuratively) an object covering over a large area, as in 血の海 (chi no umi, “pool of blood”) or 火の海 (hi no umi, “sea of fire”)

system, family / style

system / series / lineage / family

(idiomatic) A piece of cake; an extremely simple thing, something trivial, a cinch, easy as pie.

朝飯前: A piece of cake; an extremely simple thing.