a system of measurement

coordinate system

Alternative form of ヴィジュアル系 (vijuaru-kei)

that which can warm one's heart, calm one's mind and provide comfort in times of sadness

visual kei

a nervous system

(slang) denpa-kei person: one who acts strangely (disconnected from reality), often having wild fantasies and often saying strange things

aggressive in relationships

dynamical system

(slang, derogatory) A vague, derogatory label applied to stories that have overdone, clichéd elements. Usually an isekai story with elements like those described at 異世界#Usage notes.