Possibly the Greatest Alchemist of All Time

A village to the south of Bolton is abandoned by corrupt nobles, forcing the villagers to leave. The young woman Máni is especially bitter as their poverty contributed to her husband's death. Godwin plans to settle them in undeveloped land overrun by monsters and asks Takumi to establish a village. With his alchemy and his friends magic Takumi constructs a well-fortified town near good farmland and a water source in only ten days. At first the refugees are skeptical, believing they are being sent to monster-filled territory to get rid of them, so they are shocked to see an entire town with a castle and soldier barracks to defend them. Máni cannot trust Takumi and after being rude to him decides to leave the area, convinced Takumi will eventually throw her out for insulting him. Monsters attack and Máni is trapped outside the wall but Takumi saves her. Máni realizes his generosity is genuine and accepts his offer to work as his maid. Godwin is glad Takumi succeeded, but also reveals the new town is strategically located. Sidonia's Emperor is furious Barcula Kingdom has placed a town full of soldiers right next to his empire's borders. Elizabeth reveals her spell is ready. In the town everybody suddenly feels a pulse of unnatural magic, causing Takumi to realise it has been exactly one year since he arrived, meaning Sidonia has just summoned the heroes. (Source: Wikipedia)