a mantis (any of various large insects of the order Mantodea) / (by extension, from the slender build of the insect) a skinny person or horse / (rare) a fourspine sculpin, a fish of species Cottus ...

辛い: difficult to, hard to

smaller kanji historically used as a pronunciation guide, similar to modern furigana

a register, registry, list, census / enrollment, membership, registration