あいたい星人 (Aitai Seijin) is a Vocaloid song by prolific producer DECO*27, featuring Hatsune Miku. The title is a portmanteau, blending あいたい (aitai, "I want to meet / see you") with 星人 (seijin, "alien" or "space creature"), and the lyrics deliver a darkly comic portrayal of obsessive, possessive love framed through the metaphor of a lonely alien with a hole torn through its heart. Lines like "ワレワレハあいたい星人ダ" ("We are the I-want-to-see-you aliens") and the recurring exclamation "しにたい" ("I want to die") cycle between clingy affection, jealousy, and self-aware melodrama, set to a brisk 150 BPM pop-rock arrangement. Originally released as the title track of DECO*27's 2024 album あいたい星人, the song arrived in maimai でらっくす PRiSM PLUS on April 24, 2025, debuting simultaneously across Japan, international, and USA regions. It launched on CHUNITHM VERSE the same day. The music video was produced by OTOIRO, and the arrangement was handled by Hayato Yamamoto. In maimai, the song's DX chart set spans four difficulties. The Expert chart (level 9+) was designed by はっぴー, while the Master chart (level 13, constant 13.2) was designed by じゃこレモン, packing 752 total notes with a notably high 57 Break notes and 103 Slides that test the player's ability to read call-and-response patterns under pressure. The Basic and Advanced charts (levels 3 and 6) are unsigned.