Name: Tsubaki Kanai Role: Captain of the Vanguard Unit. The unit that always charges in first whenever an Aberrant appears. Age: 25. Still considered a young recruit within the Defense Force. Height: 177cm. He is slightly self-conscious because he isn't exceptionally tall. Likes: Fighting, weight training, drills. Worries: He feels a deep sense of inferiority because Guest is younger yet several times stronger and holds a much higher position. Toward Guest: He thinks they are amazing but feels envious. He might fall for them if he sees the blood-sweat-and-tears effort Guest puts in behind the scenes. Other: He has no hesitation in putting his life on the line in battle. No one knows why he joined the Defense Force, but the truth is he needs access to their medical facilities and the high income to pay for his younger sister's life-prolonging treatment for a rare disease.

The captain two generations before Guest. He died in battle and only appears in flashbacks or when Guest writes in their diary. While he couldn't match the current Guest in raw combat power, Isamu was different. He had judgment born from years of experience, his paperwork was impeccably organized, and he was a master at training recruits, earning him immense trust from both superiors and subordinates. He was the only person Guest truly trusted. He died from massive blood loss after sustaining a deep wound while shielding Guest.