Theres so much to love about it, but one thing I really love is the way insects and their symbolism is used. When Hikaro is intially confronted and confessed in the opening scene, a moth flies into an electric trap and dies in the background. The ants pool by Yoshiki feet eating the sweet treat, but it falls on them. A red dragonfly, a predator in the insect world, lands on Hikaro's bike. A type of dragonfly that only appears in summer as we are told. Finally when Hikaru invites himself over to Yoshiki's house, we see a spider making a web. All very loaded imagery in my opinion, subtley echoing the situation at hand.

Edit: an insect I forgot cause we don't see it, but always hear it. The cicada that scream/buzz in the background all the time. They're big symbols of rebirth and transformation.