My Gurren is Sparkling!!

While Team Gurren rests in a canyon, a cat-like Beastman girl named Tetori creeps up on the sleeping Kamina and inks over the lenses of his sunglasses with a marker. He wakes convinced he has gone blind and causes an uproar until an exasperated Yoko simply removes the glasses. Tetori then charms him by spraying the shades with a special cleaner and buffing them to a mirror shine, and she follows up with an offer to wash the filthy Gurren itself. Stung that Lagann gleams thanks to Simon's constant upkeep while his own machine sits grimy, Kamina agrees. The moment Gurren disappears under a mountain of suds, an enemy Gunman comes tearing into the canyon.

Kamina and Yoko pile into Lagann with Simon to run the intruder down, but the enemy flees rather than fights. The pursuit starts to smell like a trap, and just as the trio moves to turn back, a suspiciously spotless Gurren attacks them from behind. The washing was a setup: Tetori's accomplice Ziggitalis has made off with the mech. Simon tries to force a combination and reclaim it, only for Ziggitalis to produce a baseball bat scaled for a Gunman and swat Lagann aside. Enraged, Kamina leaps from the cockpit to retake Gurren with his bare hands, misses, and plummets off a cliff, saving himself by jamming his sword into the rock face. At the top of his climb back, he stumbles onto an abandoned rabbit-shaped Gunman.

Simon, badly outmatched fighting two machines, is rescued when Kamina roars in aboard his find, which he christens Usappyon over Ziggitalis' objections. Kamina batters Gurren back and orders a combination with the rabbit mech, an idea Simon hates but cannot refuse. The armless Usappyon-Lagann still lands a stunning hit on Gurren, opening the window Simon needs to ditch the rabbit and re-merge with his stolen prize. Ziggitalis abandons the hijacked mech and bolts for Usappyon while Kamina reclaims his cockpit, and the thieves escape when Tetori arrives in her own Gunman, Megaheadz, combining it with Zaolegg to spirit her partner away unharmed.

The OVA introduces the one-off Beastman duo Tetori and Ziggitalis along with three exclusive Gunmen: the rabbit-like Usappyon, Tetori's Megaheadz, and Zaolegg. It features the only Usappyon-Lagann combination in the franchise and shows Gurren stolen and recovered within a single skirmish. Both antagonists escape rather than being defeated, an unusual outcome for the series.

The short was assembled from a script rejected for the television run and is often referred to as Episode 5.5, slotting between the fifth and sixth broadcast episodes. It was released on October 25, 2007 as a bundle item with the Nintendo DS adaptation, with Hiroyuki Imaishi directing and Kazuki Nakashima writing. The decoy Gunman that lures Lagann away is visually identical to the machine that attacked Giha Village in the series premiere, though nobody on screen remarks on it. After the credits, a secret code appears; equipping the matching skill numbers in the DS game unlocks a hidden Gurren Homerun skill that recreates the OVA's baseball bat gag. Early fan translations rendered several names differently (Chitori, Jigitalis, Daorek, Usaggon) before remastered subtitles standardized the current spellings using data from the game files. The name Usappyon itself is a pun combining usagi, the Japanese word for rabbit, with pyon, the sound of hopping, while also doubling as slang for "just kidding."