二息歩行 (Nisoku Hokou) is an early Vocaloid breakout track by DECO*27, one of the most influential producers in the VOCALOID and J-pop scene. The song originally appeared on DECO*27's debut album No You, No Me (2009), a release that helped establish his signature sound, bittersweet melodies layered over electronic rock production, with lyrics that twist romantic dependency into something sharp and unsettling. The vocal arrangement features Hatsune Miku alongside additional vocals by Topi, giving the song a duet-like dynamic that mirrors its lyrical push-and-pull. The music video was produced by illustrator and animator しらこむぎ (Shirakomugi).

The title 二息歩行 is a deliberate pun on the Japanese phrase 二足歩行 (nisoku hokō, "bipedal walking"), replacing the kanji for "foot" (足) with "breath" (息) to evoke a creature that propels itself forward by breathing in sync with another being. The lyrics open with the line "これは僕の進化の過程の1ページ目です" ("This is page one of my evolutionary process"), framing the song as a twisted coming-of-age story about learning to walk, breathe, and live through someone else. This thematic richness has made the song a lasting favorite in the Vocaloid community.

二息歩行 was added to maimai as part of the GreeN PLUS update on March 20, 2014, under the niconico & VOCALOID genre. Over its lifespan in the game, the chart levels underwent numerous revisions across versions, the MASTER difficulty, for example, started at level 10 in GreeN PLUS and climbed to 13.3 by UNiVERSE+, reflecting both community feedback and the evolving difficulty standards of the maimai series. The EXPERT chart was designed by mai-Star, while the MASTER chart was handled by ロシェ@ペンギン (Rocher@Penguin). The song was removed from Chinese arcade editions starting with 舞萌DX 2021 (later revived in 舞萌DX 2022) and was ultimately removed from Asian versions of maimai DX beginning with BUDDiES PLUS on September 13, 2024, making it a historically significant track that newer players can no longer access in most regions.