The author actually plays a lot of Splatoon 3, so maybe you're onto something.Agena reeeeeally reminded me of Shiver (Fuuka) from Splatoon 3 this chapter, specially in pages 5-6.
I remember Agena also has several points in common with or very similar to Shiver: the fans, hairstyle in the front, eye shape... I thought Shiver might be an inspiration, but Splatoon 3 released way later (2022) than Agena's first appearance (2020), so It's unlikely. Later appearances though...The author actually plays a lot of Splatoon 3, so maybe you're onto something.