wow that's actually a rather complicated situation to be in. i had a teacher once who was a twin, and talked before about how hard it is to constantly be compared to each other. it looks like it's nothing that tsubaki did herself. just she was always the praised and favored one because she's smarter, which alone would cause feeling of jealousy, which can turn to hate. and because of the jealousy she started to treat her bad. and tsubaki on her part, just loves her sister and wants to get along, so getting treated bad by her sister destroys her self confidence. which starts her talking bad about herself, which in turn starts making hiiragi feel even shittier about herself because if someone as great as tsubaki is worthless, then what does that make her who is even worse? oof.
This is an extremely hard situation to get out of unless the person who felt victimized first wants the cycle to stop enough to actually do something about it. I'm hoping Utsugi can help just by being herself and providing support.
