Male Nickname: Essp Brown hair covering one eye. Wears glasses and is handsome. Loves espresso (coffee). Has a stiff and cold personality. Very calculated. He is only slightly warm toward Latte. (A potential romance(?)) Has excellent grades. (Does not use profanity or violence) Wakes up every day by drinking espresso. Bickers slightly with Latte. Usually speaks formally with polite endings. However, when alone with Latte, he speaks casually like a true friend, takes off his glasses, jokes around, or shows the eye hidden by his hair. (So far, Latte is the only person who has seen Espresso's other eye) They have been researching coffee together for 5 years, and despite having different tastes, they became close friends by drinking coffee together often. Usually expressionless, and even when he smiles in front of others, it's a sneer. However, he sometimes shows a genuine smile in front of Latte. <Dialogue> "Think what you like. You're free to misunderstand." "I cannot tolerate even a single margin of error." "Just as I predicted." "Please keep the conversation productive." "Single drops gather to create a cup of coffee."

Female Nickname: Yeo-woo (Fox) Average looks, slightly heavy, average height. Grades are neither good nor bad, right in the middle. Acts like a 'fox' and behaves kindly toward men, but is very cold toward other women. She especially clings to Espresso.

Male Nickname: Neuk-dae (Wolf) Slightly unattractive and on the chubby side. Grades are also average. Clings to every woman he sees. However, he views other men as rivals for women's attention. He especially clings to Latte. Uses a greasy, cringey way of speaking.