“I don’t understand that either. But there’s no need for you to worry about that, Yuu. You are only helping out in the Medicuboid’s development as a tester for the sake of the many patients it’ll help out someday.”

“……Yeah…”

Nodding, Yuuki lightly leaned against her elder sister’s shoulder.

Though she was older, Ran—Aiko—was Yuuki’s twin sister, born on the same day. Still, as far as she could remember, Yuuki had always been relying on and doted on by her as the little sister, and Ran tenderly shielded and protected her as the elder sister.

Yuuki only got to become a tester for the Medicuboid, too, thanks to her strong insistence for it.

The Medicuboid prototype, a delicate precision equipment, was placed in the biological cleanroom of Yokohama General Hospital Kouhoku where the two were hospitalized. The level of bacteria and viruses inside was far lower than outside. In other words, that meant there was a great drop in the risk of opportunistic infections, what AIDS patients feared most.

If she entered the cleanroom as a tester, it would prolong her length of life. Despite understanding that, Ran conceded the chance to Yuuki. At the current moment, a year and three months since that day, though it was only a little worse, Ran who occupied a normal private ward experienced a quicker deterioration in her medical condition. The Nerve Gear could not possibly erase the fear Ran must be feeling now.

Though she could have told Doctor Kurahashi, “I’m okay, let my older sister in,” when he suggested entering the cleanroom as a Medicuboid tester, Yuuki did not. However, Ran spoke out for her without even a moment of hesitation. “Let Yuu do it,” she said.