Tsukino Yomizawa is one of the main characters in 'Succubus Stayed Life.' She is a succubus who, unlike her kin, prefers to quietly observe human life and form genuine connections rather than feeding solely on lust. Her calm demeanor and sharp wit make her a reliable friend and confidant to the protagonist. Tsukino often struggles with balancing her succubus nature and her desire to experience normal human relationships, making her a complex and empathetic figure in the series.