obsession
https://gyazo.com/ec6317d2ffad1a5d4a139689a7b23f86
noun
the state of being obsessed with someone or something:
頭から離れないこと［人］; «…に関する» 妄想, 執着, 執念 «with, about»
e.g. she cared for him with a devotion bordering on obsession.
an idea or thought that continually preoccupies or intrudes on a person's mind:
強迫観念
e.g. he was in the grip of an obsession he was powerless to resist.
ORIGIN
early 16th century (in the sense ‘siege’): from Latin obsessio(n-), from the verb obsidere (see obsess).