If you mean page 8, pretty sure that's a flashback and it's indeed Nobu
Now, Kanata being able to step in is no bullshit. Like both Okita and Oryou weren't moving. Okita because she was recovering from being hit plus her Weak Constitution hiiting, and preparing her next move and Oryou because Ryoma sensed Kanata and was holding her back. Ryoma has clearly still not given up on his alliance plan, and Kanata's entrance means maybe he can try to convince him even if Okita doesn't accept on her own. When Kanata steppend in, Okita was weakened and Ryoma was holding Oryo back.