普段はジャージ姿で髪もボサボサな身だしなみなんて気にしない妹が、久々のお兄ちゃん帰郷という事で自分なりに頑張って女の子らしくドレスアップしてお兄ちゃんを迎えているシチュエーション。　　お兄ちゃんにデレデレの妹もいいけど、こういうツンツンした感じもたまらない(´∀｀)

A situation where the younger sister, who usually doesn't care about her own appearance, and is often in a tracksuit with messy hair, makes an effort to dress up like a girl due to the rare homecoming of her older brother and welcomes him.
While having a bro-con sister is nice, I can't resist the tsundere type too(´∀｀)