Warning: This Article Contains Spoilers
Tsukasa Mizugaki is a new employee at SAI Corp.'s Terminal Service #1. After failing his college entrance exams due to getting appendicitis on examination day, he sought assistance from his father, who pulled some strings to get him a job. He was previously partnered with Isla as a spotter, but was forced to become Constance's partner by Kazuki Kuwanomi.
Tsukasa is a very happy, sociable and likeable person. He easily befriended his colleagues at Terminal Service except for Michiru who acted snobish because of her seniority over him. As the story progresses, he became one of the few people with whom Isla communicates with extensively. He is shown to feel for his clients, often becoming upset when retrieving Giftia, even going so far as to seeking out a client after a botched retrieval to apologize.
Little has been revealed of Tsukasa's personal history prior to becoming employed with SAI Corp. Since joining Terminal Service, he has had only one partner, Isla, for whom he quickly developed romantic feelings. His partnership with Isla has since been dissolved. After losing Isla as a partner, Tsukasa became partners with Constance.
As previously stated, Tsukasa developed feelings for his former partner, Isla. Upon first seeing her, he thought to himself that he had already fallen in love with her, without even knowing her name. Since he was partnered with Isla, his feelings for her have grown at a steady pace. Eventually, Tsukasa confessed his love to Isla after a very passionate moment at a carnival in Eru Miru's hometown. Isla responded with fear and confusion, responding only with "I can't." Since then, Tsukasa has spoken with Isla, and she stated that she needed time to think about what to do about the situation. However, before any further progress could be made, Kazuki dissolved their partnership.
Shortly after dissolving the partnership between Tsukasa and Isla, Kazuki revealed to Tsukasa that it was part of her plan to "knock some sense" into Isla. Everything went as Kazuki had planned, and her efforts eventually culminated in Isla confessing her love to Tsukasa in front of the whole Terminal Service staff.
- "In this moment... I think I've already fallen in love with you, without even knowing your name"
- "I hope one day, you'll be reunited with the one you cherish"