Bu'er Zhang Men

As a half-shut-in who lives alone, Gu BiQiong's only goal in life is to work hard so he can pay his living expenses...
However, one day, a cute, long-legged girl who calls herself a Mohist Mechanical Puppet suddenly comes looking for him. With tears in her eyes, she hugs him and says: "Waaaah, Sect Master! We've been separated for many thousands of years, but now I've finally found you! Let's rebuild our sect and conquer the world..."

(Source: Webnovel)