Hajime Aikawa (相川 始 Aikawa Hajime) is Kamen Rider Chalice (仮面ライダーカリス Kamen Raidā Karisu, Masked Rider Chalice), a character from the tokusatsu TV series Kamen Rider Blade.
He is a mysterious man who is the Joker Undead, the most feared of the Undead as his victory in the Battle Fight would mark the end of all life on Earth. Unsealed around the time the other Undead were released, Joker battled the Mantis Undead and uses the sealed Category Ace of Hearts (Change Mantis) to become the wild card Kamen Rider Chalice. He later seals the Human Undead, who willingly surrendered to him without resistance, using the card to assume human form. The effect of prolonged use of both of these cards to assume their forms resulted with both the Human Undead's compassion for life and the Mantis Undead's fighting spirit collectively suppressing Chalice's natural destructive impulse as the Joker.
However, many of the Royal Club Undead who knew his true identity made attempts to dispose of him. One such attempt by the Giraffa Undead ended with an innocent bystander named Shin Kurihara a.k.a. Amane's father witnessing the battle being mortally wounded by accident in the skirmish. The dying photographer handed him a photograph of his family and Joker decides to protect his family in which he did to atone for his death. The Joker took on the identity of freelance photographer Hajime Aikawa since then. Though he thought less of humans originally, Hajime's time living at Jacaranda Cafe with Kurihara's family warmed him up to humans and eventually, he wished for himself to be human instead of being the Joker.
Though he and Kenzaki disliked each other earlier, Hajime's growing humanity eventually warms up to Kenzaki, who becomes a dear friend of his, then Garren and later to a limited extent, Mutsuki as well. But when the Caucasus Undead takes most of his cards, the sealed Mantis Undead among them, it causes Hajime to regress back into the Joker after attempting to resist until Leangle unseals Hajime's cards and use the Undead against him. Even after managing to reseal them all, the Joker failed to regain control and goes on a rampage until he is provided with the Evolution Paradoxa, allowing Hajime to finally have full control of himself. This allows him to even assume Wild Form, which he previously avoided to the best of his abilities, without losing control. This lasted until the Giraffa Undead was sealed, with Hajime losing control and his impulse as Joker bringing forth with the Stone of Sealing creating his army of Dark Roaches to eliminate all humans.
In the end, Kenzaki is the only one to fight him head on, with Hajime pleading Kenzaki to defeat and seal him. However, Kenzaki himself mutates into the Joker through the excessive use of King Form transformation in order to save Hajime and made his victory null, continuing the fight, retracting all unleashed Dark Roaches and prolonging destruction indefinitely. This effectively renders them rivals by instinct and they can never see each other again, or they would be forced to fight to the death for dominance the next time they meet. Moments after the battle, Hajime lives with the Kurihara family and was allowed to keep his Spirit Card to maintain the human disguise.
Kamen Rider X
Kamen Rider Amazon
Kamen Rider Super-1
Kamen Rider ZX
Kamen Rider Black/RX
Kamen Rider Kuuga