すみません、写真を撮らせていただいてもよろしいでしょうか？ — Excuse me, would it be alright if I took a photo? (Culture · Etiquette · Photography, Formal — to stranger, JLPT N3)

Gesture & etiquette

Gesture towards your camera or phone, and a slight bow.

Always ask for permission before taking photos of people, especially in more private or cultural settings. Be prepared for a 'no.' If they perform for tips, consider leaving one.