stealthy steps; tiptoeing
Refers to walking quietly and carefully so as not to be noticed, often with a nuance of sneaking or moving like a thief.
The burglar entered the room with stealthy steps.
He approached me on tiptoe and surprised me.
Compound of 盗み (nusumi, 'stealing', the continuative form of 盗む nusumu) and 足 (ashi, 'foot, step'). Literally 'stealing steps'.