余計
よけい · yokei · JLPT N2 · na-adj
unnecessary
余 (left over) + 計 (count) = counting what is left over, so too much
余 means surplus or remainder, as in 余り. 計 means measure or count. Together they name a count that goes past what is needed: too much, unnecessary.
余 — roof 亼 + wooden post/pillar
Originally a pictograph of a simple thatched shelter or hut supported by a central post, 余 meant 'lodging' or 'temporary dwelling.' It was later borrowed phonetically to write the first-person pronoun 'I/me,' which became its dominant meaning. The 'surplus/remainder' sense developed through its use as a loan for 餘.