platonic sleep friend; cuddle buddy (non-sexual)
Refers to a friend with whom one shares a bed or sleeping space purely for comfort or companionship, without any sexual involvement. Often used in the context of modern, casual relationships.
She's just a platonic sleep friend; there are no romantic feelings.
I want a cuddle buddy, but I'm afraid of being misunderstood.
Compound of 添い寝 (soine, 'sleeping together') and フレンド (furendo, 'friend'). A modern coinage reflecting casual, non-romantic intimacy.