Jamjaneun Supsogui Goemul

In a world where monsters appear and the climate changes rapidly, the only place that maintains the form of a nation is the 'Special City'. There is the infamous esper unit 'Baekgun' that is dispatched to kill monsters and absorb the outside population. Baekgun's esper Shin Hwa-Jin lives being ignored because of his origin and weak abilities. Then one day, when he hears that his twin brother, a guide, was exploited and killed by his teammates, he goes on a rampage, kills his team, and jumps off a cliff. However, when he opens his eyes, he is in the 'Library' village where he is hiding from the Special City. Shin Hwa-Jin, who lost his memory due to the shock of the jump, is saved by Tan, a man who leads the library. Tan, who lost his home and family in the Baekgun's attack, dislikes Shin Hwa-Jin who speaks the Special City dialect, but he gradually grows affectionate towards him as he loses his memory and acts innocently, naming him Hima. As he spends time with Tan and deepens his feelings and contact, Hima gradually regains his original abilities...(Source: Ridibooks, translated)