Book Ends: The first episode of season 1 and this episode, being the overall season finale of this series are both titled Amazonz.
Do Not Go Gentle: Chihiro agrees with Haruka and Jin that he's too dangerous to live, but instead of just letting them kill him, he decides to fight to live as long as possible.
The Hero Dies: Chihiro is killed in battle, off-screen, by Jin and Haruka following his rampage. If one ignores his non-canon status among mainline riders, this makes him unique as only the second main Rider to die and not be resurrected during the series after Kamen Rider Ryuki, and the only one to stay dead.
I've Come Too Far: Mamoru's opinion of his actions and what drives him.
Killed Off for Real: Chihiro dies fighting Jin and Haruka in an off-screen battle.
Killed Offscreen: Chihiro's death isn't shown even though he about to engage in a fight against Jin and Haruka.
Self-subverted. Haruka, without hesitation, allows Mizuki to kill him point-blank. She drops her hand and tells him to live.
Sequel Hook: The last moments of season 2 are Tachibana declaring a new Sigma project as there are still Amazons alive.
Shoot the Dog: Haruka killing Chihiro, knowing that Chihiro is too dangerous to live. He's pretty disgusted with himself afterwords, wanting Mizuki to kill him.
Suicide by Cop: As Iyu dies in his arms and his is mother truly dead (though he doesn't know this), he has nothing else to lose and agrees with Haruka and Jin that he is too dangerous to live, but wants to fight for his right to live.
Taking the Bullet: Mamoru is killed when he attempts to stop a High Pressure Round from hitting Nanaha.
Together in Death: The final shot suggests this with Chihiro, his mother and Iyu.
Tragic Monster: Due to his unique biology, Chihiro is incredibly dangerous to humanity despite not doing anything directly. Despite his attempts to remain human, he realizes that he's too dangerous to live and in the end, he dies fighting Haruka and Jin. For bonus points, he's was at most chronologically four at his time of his death.
