Ah, the classic sibling "Hey, only I'm allowed to talk about my [brother] that way!"
That does seem tsundere. Adding the tag back in, as originally found on Pixiv.
Nothing unreeeasonable about Akebono-san being mad at hiiiim.Dropped at 2-4He's the one at fault for using up all our steel without any discussion about it, don't you think?I don't want to work.The next day.Not really.His behavior was imprudent, riiight?Shouldn't you have calmed down, already?Ufufu!He's the type that'll destroy himself in the future with gambling, isn't he?Strained AtmosphereHearing this is making her a little upset.