Vocaloid

Imitator - Kaito

In this song, (which belongs in a series as well with 'The Riddle who won't solve riddles' which is sung by Rin)Len, the detective, is singing to Rin who is a witness in a murder case. Len repeatedly asks Rin "So, who is the culprit" (SPOILERS) which by the end of the song Rin realizes that the murderer was Len.   

Kagamine Len The Riddler Who Can't Solve Riddles

Five nights at Freddies- The Living Tombstone

KAITO Imitator

Len and Rin  - Servant Of Evil

Vocaloid - Kagamine Rin - Kokoro

2nd version (with a better quality) : https://soundcloud.com/len-kagamine-02/alternative-ver-rin-kagamine-tokyo-teddy-bear

Vocaloid

Jasmyn Honegger