The best part of this is that he's openly admitted it to one of Yamada's friends, as well as vocally admitting it to himself. That's some huge progress.
And it's good that Moeko shut that other girl up. If she said Ichi and Yamada were going out, he would have either had to deny it there (and open her back up for the pickup bastard) or lie and confirm it, which would have caused problems of its own.