Word of God came in at the end of Volume 31 and revealed that Eishun IS an Aoyama.
Apparently the family is actually rather large, and he's not so close as a brother to Motoko. There's plenty of room for an extremely skilled but ultimately cadet line member of the family to exist as an outcast. Of course, Tsukiyomi's never really been all that stable, her progress in the Shinmei school may also be associated with the members of the family recognizing that she was dangerously psychotic on top of everything else.
- Grumpy Uncle Gearhead
Apparently the family is actually rather large, and he's not so close as a brother to Motoko. There's plenty of room for an extremely skilled but ultimately cadet line member of the family to exist as an outcast. Of course, Tsukiyomi's never really been all that stable, her progress in the Shinmei school may also be associated with the members of the family recognizing that she was dangerously psychotic on top of everything else.
- Grumpy Uncle Gearhead