|The Prince of Tennis|
|Season 6, Episode 163|
December 8, 2004
The Golden Pair's Memories
| previous arc|
Junior Selection Team VS US Coast Team arc
| next arc|
Kaidoh's Unknown World is the 163rd episode of the Prince of Tennis series.
Kaidoh loses his memory temporarily after he hits his head hard on the floor, saving Echizen from an incoming tennis ball.
He gets annoyed and frustrated and a little scared at the Seigaku member's failed attempts to revive his memory, and so he runs away. However, he unfortunately runs into St Rudolph's Mizuki and Yuuta, Mizuki learns that Kaidoh has lost his memory and uses this as a chance to recruit Kaidoh as a member of St Rudolph by tricking him and telling him lies about Seigaku and saying how Kaidoh was a St Rudolph member. However, before Kaidoh can sign a contract that declares him as a member of St Rudolph, Momoshiro and Echizen find him and stop him. This leads to an argument between the two schools and results in a match. Echizen and Momo versus Kaidoh and Yuuta. If Kaidoh and Yuuta win, Kaidoh will be a member of St Rudolph.
During the match, Momoshiro and Echizen purposely lose points by hitting easy shots to Kaidoh so he can hit a "Snake" and a "Boomerang Snake" to revive his memory. However, it is only until the match is at 5-1 that they realise they should play seriously in order to keep Kaidoh in Seigaku.