Love Lab (恋の実験室 Koi no Jikken-Shitsu "Laboratory of Love") is the 19th minigame of Rhythm Heaven. The playable main character is a scientist student who has a crush on her senior lab partner, and she, her senior partner and another student are conducting an experiment. When getting a perfect, the gift "Lab Journal" will be available to read in the Café.
The male scientist student gets a flask tossed to him. He will shake the flask a number of times and toss it to the female student (the character played in the game). The flask must then be shaken the same number of times he shook it by relying on the tone of rhythm in the game. The player then must toss the flask to the other student in the lab. If the flask was shaken correctly and in time, all of the hearts made by both students will be combined and fall into the white bag.
Hold down stylus: Grasp flask
Slide: Shake flask
Flick: Toss flask
Hit: The flask is grabbed and then tossed to another scientists. The hearts will combine and fall into the white bag once you shake the flask to make more hearts.
Barely: Grabbing the flask too early or too late will result in a heart either not coming out or floating away. A "Barely" counts as a miss.
Miss: The flask is not grabbed or is not tossed, it falls onto the counter and breaks into pieces. If the player holds the flask and does nothing, holds or shakes off beat, their hearts will not combine with the senior lab partner's hearts and float away instead. The senior's hearts, if left uncombined, will dissipate into skull shaped vapors.