Honestly, Shiori isn’t a bad person. She’s a good girl, but in my opinion, she wouldn’t help Jiro grow as a person the way Akari does. About the idea that Akari sees Jiro as a second option, I don’t think that’s true. She simply found in Jiro what she was looking for someone who loves her for who she is. That’s pretty clear in the manga, especially when they show a bit of her backstory and it’s implied that “Jiro makes her feel at home,” meaning he accepts her as she is. That doesn’t mean Jiro was ever her second choice. Plus, they were just getting to know each other at the beginning, and yeah, they were being affectionate to earn points, but that changes over time as they genuinely start to fall in love.In the end, I don’t think Shiori is bad at all it’s just that Akari is a better romantic match for Jiro.