nita-nita
Grinning in a somewhat creepy or mischievous way. Unlike 'nikoniko', this smile makes others uncomfortable.
💡Someone grinning while reading a private message — 'He was nita-nita looking at his phone, making everyone curious.'
何がおかしいのか、にたにたと笑っている。
He's grinning nita-nita for some unknown reason.
He was ___ to himself, clearly plotting something.
何か企んでいるのか、一人で○○と笑っていた。