Translation guide
The English idiom 'head over heels' means being completely in love or deeply infatuated. In Japanese, there is no single direct equivalent, but several expressions convey a similar intensity of romantic feeling.
Expressing that someone is totally in love, often in a giddy or overwhelming way.
Literally 'neck-hooked', meaning completely captivated or head over heels in love. Casual and commonly used in romantic contexts.
Do not translate 'head over heels' literally as 頭がかかとを越える or similar. It will not be understood.
He's head over heels for her.
Means being deeply in love, often with a nuance of being completely devoted. Slightly old-fashioned but still used.
She's head over heels for him.
Means being absorbed or crazy about someone/something. Can be used for love, but also for hobbies. When used romantically, it implies being head over heels.
He's head over heels for his new girlfriend.
Slangy term meaning to be completely smitten or infatuated. Conveys a sense of being foolishly in love.
He's totally head over heels for her.