User blog comment:Ryousama96/is this cheating/@comment-5916265-20130627112652/@comment-9505008-20130627134429

Mmm... not quite. If the invitee had a full Daemon Scroll at the time s/he encountered Odairi, Odairi would've been sent to the inbox. Since obtaining is defined by having it in your scroll, this wouldn't trigger the invitation bonus. This also answers explains the rare summons conundrum.

Still, it is a bit far-fetched that he got FOUR of his friends to do this...