I'm sure you heard of seimei handan. It was proposed after Meiji era, at a time when people started to use last names and were becoming more and more interested in the good or bad quality of the name. It's like you're making a promise to your child of what they're to become, or what it's expected of them.

(although he says all this, there's a part of him that feels like she already knows of it. he takes a large inhale, letting the smoke leave through his nose.)

Although I'll admit, it's likely that 'Watanuki' isn't my real name.