Well, I'll keep this short and sweet.
Your topic poster child above -- Tatsuya Shiba from
The Irregular at Magic High School --is one of the first one's I thought of, so I'll skip that one.
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Koyomi Araragi from the
Monogarari Series. Araragi is my runner-up to Tatsuya Shiba. He honestly demonstrates brotherly love (if not more) to all the females in his odd life, although that can take some strange turns. This includes his relationship with his two equally eccetric younger sisters.
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Tanjiro Kamado from
Demon Slayer (
Kimetsu no Yaiba). For obvious reasons. Tanjiro is a truly good young man who loves his family and wants to save his sister Nezuko from her fate. I don't have to say much more than that, as everyone here should know that by now. If not, go watch it
now.
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Edward Elric from
Fullmetal Alchemist, Again, for obvious reasons. The whole premise of the series (both of them) is that Ed will do whatever it takes (almost) to keep his promise to his younger brother, that he will restore his body back to normal. The efforts, blood, sweat and tears they go through for that purpose bespeaks of Edward's love for his younger sibling.