At eight years old, Yatsuhashi unlocked his Semblance when he accidentally made his dad forget that he’d already given him his allowance and got another three Lien.

It had taken him a while to figure out how his Semblance worked, and whenever he told his parents and grandfather what it was, they immediately forgot about it. For years, it was a way for him to get out of trouble when he did something wrong, or to get an extra serving of dessert.

At first, Yatsuhashi had excused this mischief as “experimenting” and it seemed mostly harmless. Over time, he learned that it was easiest to get someone to forget something they didn’t care much about. A fleeting thought or a stray remark, made without much intent. But if an idea was more firmly fixed in a person’s long-term memory, he could only make them lose it for a short period of time.

- RWBY: After the Fall, Chapter 7