Sorry for the delay, I hope this is worth it!
RE-SETLIST
Difficulty: 6
Six Vocaloids decided to put on an interesting type of performance, where collectively they would perform six songs, where each was either a duet, a trio, or a quartet. Miku, Len, Rin, Luka, Gumi, and Kaito each decided which songs would be performed (one of which is Remote Control) and who would be performing in each. Assume that any song can be any type of performance. Based on the following clues, determine the order of the setlist and who will be performing.
1) Two Vocaloids each performed 2, 3, and 4 songs. Two performances each were duets, trios, and quartets.
2) The second performance featured all Vocaloids in Matryoshka and included two other performers.
3) Luka (who performed fewer times than Kaito) sang in two performances of the same type (duets, trios, quartets) at least once.
4) World is Mine was the first song after Len's last performance.
5) Kaito performed with Len exactly twice, but never performed thrice in a row.
6) Both duets were consecutive.
7) Between the fourth and fifth performance, only one Vocaloid remained on stage.
8) Himitsu Keisatsu was performed sometime before both duets.
9) Len performed once with everyone but Rin, who didn't perform in Trick and Treat, the last song.
10) Luka was in the first performance, which was not Himitsu Keisatsu.
11) Meltdown was not the first song.
12) Len's three performances are all consecutive.
13) Gumi performed neither in the fifth song nor in World is Mine.
14) Miku performed at least first and last, neither of which were a performance of World is Mine.
15) Gumi only performed in quartets.
16) The first song featured fewer Vocaloids than the second did, and exactly two performers remained on stage between the two songs.