炉心融解 (Roshin Yuukai)

Background
There are various interpretations of this song. The PV can be literally interpreted as Rin jumping into a nuclear reactor to commit a martyred suicide or figuratively as Rin trying to get rid of her past or to purge herself of her sins, and leave it behind in order to grow up and become an adult.

Iroha says the lyrics and video represent conflicts of inner psychological world. In the video, Rin jumps into a reactor core/nuclear reactor and chokes someone, possibly to death. The little Rin stands for innocent childish mind inside her. The choking scene symbolizes erasing her past self and starting a new.

The Controversy
There was a controversy over the video related with the Weekly Vocaloid Ranking. Taking advantage of the Vocaloid Ranking's score system, the people made dummy accounts and put the song on their MyList, just to increase its score in the ranking, making it stay in the top 20 indefinitely. Though iroha(sasaki) asked the viewers to stop the illegitimate scoring, it did not end and in retaliation, Iroha deleted the video from his account and put it up on Nagimiso.SYS's. This disqualified the video from being in the Rankings as one of the requirements is that the original composer must submit it.

This raised the awareness of the cheating behind the Rankings. The score system of the ranking was modified, thus taking many long-lasting regulars such as Hatsune Miku no Shoushitsu, Miku Miku ni Shite Ageru, and World is Mine off the list altogether.

The new PV put up on Nagimiso.SYS's account features several touched-up areas including a different-looking reactor, new countdown text, and added detail in certain scenes.