Kamen Rider: the Me No One Knows

Lu Yuan is an orphan. Since he was six years old, he has dreamed of an endless corridor every night, and someone behind the door taught him how to fight, accelerate, and change shapes. They called him "The Heir," but they didn't tell him what he inherited. At eighteen, the monster arrives. He discovered that the corridor was not a dream. He put on armor that didn't belong to this world and fought in the alleys late at night. Every time he fought until his bones cracked, because someone was waiting for him to go back. Lin Zhixia, the girl who has been sitting next to him since the nursery. She didn't know his secret, but she always handed him a glass of warm water when he woke up. Later he learned that all the monsters came because of him. As long as he lives, the disaster will not stop. The final door opened. Push it away and it's over. The price is that everyone forgets about him. He pushed away. Reunited many years later, she said: "I always feel that this is not the first time you have helped me carry things." He smiled. She doesn't know, and he doesn't remember. But having someone by his side is enough.