ase_kaichatta_ne_cesario_(vocaloid)
EN: You worked up quite the sweat there, Cesario (racehorse).
Infamous Vocaloid song singing about making onigiri with sweat from Cesario the racehorse. Sung using Hatsune Miku's voicebank.
The song was quite the meme during the old 2ch and Niconico days, though it recently made a comeback because of the horse's Umamusume counterpart being announced, leading her to be strongly associated with onigiri, making them while sweating or just refering to the song while she's sweating or when eating an onigiri she has made.
Lyrics
Original JP
9月だというのに
たくさん汗をかいた シーザリオ
またがっていた（またがっていた！）
僕の手にはびっしょりシーザリオの汗
両手を広げて吹かれる 時間を忘れた
手にできた結晶を
僕はおひつを開けて おにぎりを握った
おいしいね シーザリオ
EN translation
Even though it's September
You worked up quite the sweat there, CesarioI sat astride you (astride you!)
With my hands drenched in Cesario's sweatI spread my hands with the wind blowing and forgot the time
The crystals I've got on my hands
I opened the rice container and made a rice ball
It sure is delicious, Cesario