This outfit has a futuristic flair to it, with monochrome core coloring and yellow accents. A careful eye will notice the sockets in her back for angel wings. 
— Website description[1]
Kokoro (ロミオとシンデレラココロ? lit. Heart) is an Outfit for Kagamine Rin.
Description[]
The Outfit's attire consists of a mostly white, cybernetic dress with black sections over the collarbone area and a pleated layer on the bottom, and a neon-yellow collar. Yellow accents strike in the middle and bottom of the dress with neon-yellow plates on the sides in between the black and white portions, and four sockets appear on the center of the dress with two on each side and all of them have small, neon-yellow wires sticking out. There are also black and white gloves with yellow cuffs, matching boots, and rusty-gold, mechanical angel wings with red and blue wires held on each side.
Additionally, Rin's irises become lime-green, her hairclips become sockets matching the ones on her dress, her headphones have white earpads with yellow centers, lime-green lighting on one side and and yellow components attached on the other, and her bow is attached to the headphones with a yellow components with neon-yellow light.
Game appearances[]
The Outfit firsts appears in Hatsune Miku: Project Mirai 2 where it can be unlocked by clearing "Kokoro" on any difficulty and can be bought for 5000 Mirai Points. It returns in Hatsune Miku: Project Mirai DX with the same unlock conditions, though it now costs 3000 Mirai Points to buy.