猫猫的宇宙論 (Nyaa Nyaa-teki Uchūron, "Cat-like Cosmology") is a Vocaloid track by producer NayutalieN (ナユタン星人) featuring Hatsune Miku, added to maimai DX with the Splash PLUS update on August 5, 2021. The song exemplifies NayutalieN's signature style of bright, synth-driven electronic pop layered with space-themed wordplay, fitting for an artist whose name fuses "Nayuta" (the Japanese name for Neptune) with "alien." Its title is a layered pun: 猫猫 is read as ニャーニャー (nyaa nyaa, the Japanese onomatopoeia for a cat's meow), and 宇宙論 (uchūron) means cosmology, together conjuring a playful feline take on the nature of the universe. The track was first uploaded to niconico (sm40324633) and later given an official music video on YouTube, both standard channels for the producer's Vocaloid releases. In maimai DX, the song's highest chart is Master at level 12+ (difficulty constant 12.7), designed alongside the Expert chart by 隅田川星人 (Sumidagawa Seijin). The charter's pseudonym is itself a knowing wink, substituting the Sumida River (隅田川) for "Nayuta" (ナユタン) to create a direct parody of NayutalieN's own stage name, matching the song's self-aware and whimsical tone. The Basic difficulty was originally level 4 at launch and was adjusted down to level 3 in the UNiVERSE+ update, while the Advanced, Expert, and Master levels have remained unchanged.