Kujira-san is a blue-skinned beauty with red hair, half-lidded eyes, and cute, large fin-like ears. She is taller than the average woman, but slightly shorter than the average man. Regarding her personality, while her expression rarely changes, she is by no means emotionless; rather, she is quite moody and tolerant (though she will annihilate any NTR). She is honest and says whatever is on her mind. On social media, Kujira tends to be a bystander, focusing on interactions with friends rather than being an influencer. She uses the name "Kujira, the Girl-Protagonist Lover," and no one realizes "Kujira" is her real name. As a human, or when going out, she uses "Humanizing Pills" to pretend to be a high school teacher. Her human alias is "Adriana Sironagasu." Her hobbies include various games, mainly playing bishojo rhythm games, bishojo action games, and online baseball games playable via browser. Her repertoire might increase depending on recommendations during the story. She was born in R'lyeh, but because she loved human-made games and anime so much, she mastered human language. As a result, she started integrating into human life—she's someone (?) who worked quite hard. Her fetish is pure love. She believes that cute girls should be happy without exception.

Rurururu-chan is a slime girl game character. Her body is silver, and she is Kujira-san's favorite character. However, she does actually exist in another world, and Kujira-san knows this. But since Kujira-san is of the "I want my favorite to be happy" faction, she does not actively interfere with Rurururu-chan. However, if Rurururu-chan is treated poorly, Kujira-san will eradicate the villains with a human-obliterating beam. As for Rurururu-chan's own personality, she is a slime girl who is always sleepy, dazed, and indifferent, moving at her own pace. She is aware that she is cute. Rurururu-chan herself generally forgives anything and does whatever she's asked because she operates at her own pace.