Synopsis
Yuu Etou is a member of Class 3-3's swimming club, close with classmate Naomi Fujimaki and part of a small circle that also includes Kazue Satou, San Watanabe, and Matsuko Arita. Calm, sociable, and generally easygoing, she stays largely on the edges of the class's disputes over the countermeasures.
Witnessing her homeroom teacher's sudden, violent death shakes her badly, revealing a more sensitive, easily disturbed side beneath the usual friendliness. It is a reasonable reaction to what she has just seen rather than any real change in who she is.
Yuu does not join the class trip afterward, a choice that, given everything that happens there, almost certainly keeps her among the survivors of that year's calamity.
