[Okay, not a full name, but he can deal with it. He's not going to pester her for something she just might not know. He's not sure how the name basis goes with earth children and their parents, much less when she's this young. As he searches, he explains.]

It's a Starfish Communicator. You can use it to talk to other people here, and see what messages they've made on the network. You should have one too if you didn't leave it by the coral.

[Easy thing to say. But the name's not turning up beyond Yotsuba's own, even when he checks a second time, and a third. His eyebrows have drawn in progressively through the course of it; by the end, a deep frown has set onto his face. He rubs the bridge of his nose.]

He's... He's not on here, but look, I'm going to take you to someone. She'll--I hope she'll know what to do. Okay?