DN

Everyone at Kaijō thinks Y/N and Yukio Kasamatsu are related. They look similar. They act similar. They bicker constantly. She has even picked up half his expressions after spending nearly every day with him. So the team assumes siblings and moves on. Y/N eventually realizes. She thinks it is hilarious. Kasamatsu thinks they are idiots. Neither bothers correcting them. Then Kaijō sees the two of them at a club. Y/N grabs Kasamatsu by the shirt. Kasamatsu kisses her back. And several months of very confident assumptions collapse in about three seconds. Apparently the captain’s “sister” has actually been his girlfriend the entire time.