プリティパンティ☆悪マリン (Pretty Panties ☆ Aku MaRin)

Background
プリティパンティ☆悪マリン (Pretty Panties ☆ Evil MaRin) is an original song by uniMemo-P featuring Kagamine Rin. It is part of the AkuMa Series.

The song starts with two demon girls called "MaRins" entering Len's room on Christmas Eve to play some pranks on him. Len panics as he was expecting Santa Claus and asks who they are. The girls present themselves as "Pretty Panties☆Aku MaRin", and wish him a "Merry Christmas and Happy Birthday", then proceed to give him a "Christmas gift". With the magic words "Rin Len Laririn", they strip Len and dress him in the majokko school swimsuit from "the Rampage of Kagamine Len".

The girls mock a confused and angered Len, saying that the suit fits him very well. However, as the girls failed in their "real mission", they bid their farewells to Len and leave the room through the window they used to enter. Len, humiliated, is about to protest when Miku enters his room and complaining about the noise finds him dressed in the swimsuit.