I meant to set up a weekly reminder to post a VocaJazz item every Saturday evening until Spring, but didn't – so here it is tonight instead.
Miku here performs After-School ChocoCup, which lyric-wise seems to be in the same broad vein as those occasional Manhattan Transfer nonsense songs, as the supplied English captions show (note: captions not subtitles, so you'll need to ensure that player option is left switched on).
The YouTube page for this says that it was composed by Chae-P (music) and Ryootai (lyrics); but another version says it is from OSTER project, whose former name was Fuanari-P, so there is some confusion here. The song does appear in the OSTER project entry at the Vocaloid Wiki, at number 34 in the song-list there, under the slightly different title After-School Chocolate Cup Show. It is the same song, though, without the opening count-in in that other version.
It is difficult, by the way, to find VocaJazz videos with an English translation provided, which is why (for example) I haven't yet featured any Meiko items. Meiko's mature voice is good for jazz, so I shall keep looking.
In the meantime, this is pleasant enough, quite relaxing in fact, and a good choice for this rainy day. Who couldn't do with a choco-cup right now?