 If you liked Subaru |  ...then you might like Kokou no Hito |
They both focus on one character's very long journey to perfection and extremely in-depth understanding and mastery of their respective fields (Kokou no Hito - mountain climbing, Subaru - dancing). The protagonist is all that matters, Subaru gets a lot of people who help or try to hinder her in her task, recurring characters, while Kokou no hito much less, i literally cannot remember more of them than like 2 that show up for more than a few chapters. Both protagonists only care about achieving greater heights and understanding of what they do, neglecting social life whatsoever, feeling lonely, isolated and not understood by anyone.