すみません、お風呂は今、空いていますか？ — Excuse me, is the bath available now? (Ryokan · Guesthouse, Formal — to staff, JLPT N4)

Gesture & etiquette

Slight bow.

Be mindful of bathing times if there are specific schedules for gender or private use. Always check with staff before entering if unsure, especially with shared family baths.