Pokemon Adventures: Black and White Vol. 5 (manga)

White tests out a Pokémon battleground prototype: the Battle Subway. Meanwhile, Black is happily reunited with an old friend...under unhappy circumstances. Then Gym Leader Clay reveals a dangerous secret. Now Black must prove himself to the other Unova Gym Leaders so he can join their team to fight a common enemy—an evil organization that might jeopardize the Pokémon League Championship itself! Will Black earn the trust of the Unova Gym Leaders in time...by ringing a bell?!