I'd have Santino hold it and continue his reign for now. Yes, it's crap, but it's just temporary. While that happens, I'd try to build up Lord Tensai by having his matches more quick paced and make him beat stars higher on the card (Kofi, Truth, Ryder, maybe even Khali, for Tensai to chokebomb him and make him look strong).
If he gets over, start a feud with him against Santino: after Santino beats, lets say, Jack Swagger, Tensai attacks him with that claw thing he does after matches. Then, have Tensai win a one on two handicap match against... hum... Tatsu and Ryan, The Usos, IDK. Santino is wrestling Otunga, when Tensai interferes throwing salt on his face and David wins. Johnny comes out and makes Tensai the #1 contender for the US Championship for... Over the Limit, if it goes on this pace. The Raw before the PPV, Tensai and Swagger vs Santino and Kofi. Santino pins Swagger, Tensai attacks Santino and Kofi, chokebombs both, attacks Jack for getting pinned and does the claw thing on Marella again.
PPV: Tensai dominates the match for the most part and Santino makes his sequence at the end (punches, hip toss, headbutt) and goes for the Cobra. Either LT no sells it or sells but kicks out at two, either one is the same thing. Bicycle kick, Baldo Bomb, Santino can't continue. Tensai wins the United States Championship.
The Raw after the PPV (last one after house show on Brazil, btw) Lord Tensai grabs the mic for the first time. He rants about how the US fans treated him like crap and got him nothing, then he went to Japan and became huge there, how the japanese fans are more supportive, things like that. He then throws the US belt away and reveals a custom made Japanese Championship. The next week, he beats someone and is attacking them post match (Santino's rematch?) until Brodus Clay saves the face. This starts a feud between Tensai and Brodus for the title that goes on until Money in the Bank.
:tensai: