I let you and you alone use it all the time.

[And it's true. If anyone else were to try calling him that, he'd tell them to knock it off. From Isamu, though, it feels like an affectionate nickname rather than an actual title.

When Isamu tries to stop him from bundling up, he pauses, looking a bit put out.]

It was freezing cold when I was out there earlier this morning. I'd rather not take my chances with the temperature.