A mean anime brother might manipulate, mock, or even harm their sibling, while a great anime brother provides all the emotional support their brothers or sisters need, and they may even look after their parents if need be. These outstanding anime brothers may also extend their kindness and generosity to their friends and classmates.
In Demon Slayer, the nine mighty Hashira are the pillars of the Demon Slayer Corps, while protagonist Tanjiro Kamado was the pillar of his own family. He helped his widow mother look after his younger brothers and siblings, and they all deeply loved him. Every time Tanjiro went to town on errands, the rest of the family missed him.
That's the kind of outstanding brother Tanjiro was, and still is. Only Nezuko remains by his side after the slaughter, so Tanjiro will push himself to the absolute limit to defend his little sister and restore her humanity however he can. It's his life's mission as a responsible brother.