I puzzle over why he was so quick to accept, when suddenly...

“Astral Break.”

...he  uses  Valkyrie’s  special  move,  which  is  effective  against  ghosts.  Chains emerge from his palms before tightly wrapping around one of the ghosts. Seiya then looks at the firmly bound monster and nods.

“All right, Kiriko. Try attacking this incapacitated ghost.”

***

Volume 5, Chapter 49