Hiyosu

Hiyosu is inquisitive, excitable and possessive about unusual research material. He reacts to Rukia’s Gigai with intense scientific enthusiasm and immediately wants to dissect its construction.

He is also blunt with his colleagues, regularly ordering Rin away from his sweets or asking for assistance. During emergencies, however, he concentrates on protecting the institute and preserving its communications.

Hiyosu’s extendable eye allows him to inspect objects at very close range. The series does not explain who created the mechanism or whether his other unusual physical traits are technological modifications.

He can erect a Kidō barrier around the institute, attempting to isolate the building when it is breached during the Quincy invasion. He carries a Zanpakutō, but no release or named combat technique is revealed.

Hiyosu examines Rukia’s Gigai and determines that its construction exceeds the work of current Soul Society technicians. The discovery supports Akon’s conclusion that it was created illegally by someone outside the organization.

He later helps detect Yammy Llargo and Ulquiorra Cifer’s arrival in Karakura Town. During the Wandenreich invasion, he assists with communications and tries to seal the compromised institute. He survives and remains at work in the epilogue.

Akon and Rin Tsubokura are Hiyosu’s principal laboratory colleagues. He trusts Akon’s judgment and frequently gives Rin practical instructions.

Rukia Kuchiki’s Gigai becomes an object of his professional fascination. Kisuke Urahara is its illicit creator, although Hiyosu does not initially name him.