ハジマリノピアノ (Hajimari no Piano) is an original instrumental piano composition by ゆゆうた (Yuyu-uta), a Japanese pianist and YouTube creator best known for his covers, original pieces, and collaborations with other entertainers. The track first appeared in SEGA's CHUNITHM CRYSTAL as part of its launch song pool, then crossed over into maimai DX Splash PLUS on April 1, 2021, an April Fools' Day release that the developers treated with characteristic cheekiness. To mark the occasion, SEGA released a promotional video showing Yuyu-uta being humorously kidnapped by the maimai mascot Happy and the CHUNITHM mascot Chuni Penguin, who frog-marched him to an arcade cabinet and forced him to play his own MASTER chart on the spot. Running 2 minutes and 27 seconds at 190 BPM, the piece is a purely instrumental showcase for the piano, no vocals, no lyrics, just rapid arpeggios and a melodic line that shifts key with unusual frequency. The composer himself informally noted roughly 28 modulations across the track, a feature that gives the song a restless, episodic feel. The maimai chart set comprises four DX difficulties: BASIC and ADVANCED serve as lower-level introductions, while the EXPERT chart (by ぴちネコ) and the MASTER chart (by はっぴー) push players into denser territory. The MASTER chart at level 13+ leans heavily on Tap notes (849 of the 982-note total), demanding sustained stamina and crisp execution against the unrelenting piano line. The collection title earned by playing the song, "ピアノ打って頂戴" (Play the Piano Please), winks at the Takemoto Piano CM song that shares an association with the composer's output.