I'm Just an Ultraman Passing Through

[Single heroine + no System + time travel.] A boy who loved Ultraman saw a giant clad in silver and white when he was young. The two made a promise to meet again after the boy turned eighteen. When they reunited, they set out to provide humanitarian aid in the worlds of other Ultra Warriors. Alien: Who exactly are you? Saint Jia Ultraman: I’m just an Ultra Warrior passing through and beating people up. Remember that.