Board Thread:Questions and answers/@comment-27279375-20170523191830/@comment-30711988-20170523201323

I think you meant "mysterious".

That was Kazuma, pretending he is Terumi. That's when he started to work with Seven and Eight behind Nine's back.

"That man" who approached them talks like Terumi, he is someone they knew already, and he got past their radar because he came with Nine. Also, Terumi went back while the other group was on their way to the cafe, and he returned to them after Nine and Celica joined them. Later, Seven and Eight mentioned "that man" again, and Seven was wary of him since that guy betrayed someone before teaming up with them. Terumi complimented the two when he observed Takemikazuchi, and in the next novel they revealed that they were able to summon Takemikazuchi with "that man"'s help.