"Help me, あーりん！" is a Touhou Project arrangement brought into the maimai ecosystem via the CHUNITHM crossover. Performed by the fictional band Irodorimidori (イロドリミドリ), a group of voice-acted characters originally created for CHUNITHM, the song is a cover of Beat Mariō's (ビートまりお) "Help me, ERINNNNNN!!", which itself remixes ZUN's "竹取飛翔 ～ Lunatic Princess" (the stage 6 boss theme from Touhou 8: Imperishable Night). The arrangement was handled by Yuuya Kobayashi of IOSYS, with lyrics by Daisuke Watanabe (credited as Lettuce Shichijou). The maimai version uses a slightly shorter audio cut (2:27) compared to the original CHUNITHM release (2:49). The song debuted in CHUNITHM PLUS on April 1, 2016 as part of an April Fools event, its original WORLD'S END chart famously contains over 4,000 notes, a comedic barrage befitting the gag. Regular charts followed in CHUNITHM shortly after. The track later crossed over into maimai MiLK PLUS on October 16, 2018, where it sits in the オンゲキ＆CHUNITHM genre category. In maimai, the background renders as a still image rather than the animated visuals seen in CHUNITHM, and the audio follows a composition close to the "Help me, ERINNNNNN!! (Band ver.)" arrangement. The title is a deliberate portmanteau pun: "えーりん" (Eirin, referencing Touhou's Eirin Yagokoro) becomes "あーりん" (Aarin), a nickname for Aliciana Ogata (CV: Ayaka Fukuhara), the guitarist character from Irodorimidori. The jacket art depicts the three vocal characters, Aliciana Ogata, Serina Akesaka (CV: Emi Nitta), and Nazuna Tennouzu (CV: Ayano Yamamoto), cosplaying as Eirin Yagokoro, Kaguya Houraisan, and Tewi Inaba respectively, directly tying the Irodorimidori cast to the Touhou characters referenced in the lyrics.