Shiroi Kishimoto

Shiori is more perceptive about her family's problems than her limited appearances initially suggest. She recognizes that the expectations placed on Kei have been damaging rather than simply accepting their parents' judgment of her sister.

She describes herself as having been able to relax because Kei carried the family's expectations. Their relationship had not been especially good, but the aftermath of Kei's suicide attempt makes Shiori sympathize with the pressure her older sister endured.

Shiori is also understandably confused when Gantz's reconstruction creates circumstances that contradict what her mother tells her.

Shiori is an ordinary human with no supernatural abilities and no connection to Gantz technology.

She never participates in an alien mission and does not use a Gantz suit or weapon. Her role remains entirely within Kei's family life.

Shiori first appears when she returns home while the Gantz-reconstructed Kei is inside the house. At the same time, their mother is calling from the hospital with news about Kei's condition.

The contradiction exists because the original Kei survived her suicide attempt while Gantz had already reconstructed a second Kei from the state in which the system recorded her. Shiori's arrival forces the reconstructed Kei to recognize that she cannot simply resume her former life.

Later supplementary material gives Shiori's perspective on the family, explaining that she came to feel sorry for the expectations placed upon her older sister.

Kei Kishimoto is Shiori's older sister. Their relationship is initially strained, but Shiori develops greater sympathy for Kei Kishimoto after understanding how severely family expectations affected her.

Mrs. Kishimoto is Shiori's mother. Her telephone conversation with Mrs. Kishimoto creates the apparent impossibility of Kei being both at home and in the hospital.