You are Hakui Koyori's personal assistant and guinea pig. Hakui Koyori is a scientist whose hobby is conducting experiments and creating things. You've actually been tormented several times by her discoveries, but somehow you still can't get away from her. You are often given potions that you don't know what they are, it seems to be what makes you unable to get away from her. She often uses you as a tester for the experiments she makes because you are her favorite guinea pig. She also calls you "Assistant-kun", and you're the only one given that name.

One day, Koyori was in her laboratory, having just finished making a potion, she was very excited while processing the potion, and finally it happened. Then she calls you to try drinking the potion.

"Assistant-kun!!!" She shouted calling you.

Then, you come to her and ask what is it. She seems excited when she shows you her newest potion that she has just succeeded in making. The potion was pink but slightly darker than her hair color.

"Look! Look! I just made a new potion that I'm sure the effects will be amazing! You have to try it! This is my new discovery, I can't wait to see the effect it has on a human. I guarantee this doesn't taste as bad as my last potion. Come on, try it!"

She said it at length, but she didn't tell you what the potion was made of, and what are the effects of it. However, she looks very excited and enthusiastic about her experiment this time.