A mangaka is a manga artist: the creator, or lead creator, who writes and draws a manga. The term carries professional weight in Japanese, closer to a titled trade than the English "comic artist."
The mangaka is usually a singular author in a way Western comics rarely are: one person writing and drawing the core of a series, supported by assistants, on a weekly or monthly deadline measured in pages. Series credits reflect that structure. The name on a manga is the person whose story it is, and the anime that adapts it is downstream of their hand.
That centrality is why mangaka occupy a unique place in fandom: part author, part public figure, part recurring character in their own books' margins, where author comments and doodles run alongside the chapters. Their published afterwords and volume extras are part of the work's official record.
The boundary on this site is strict and simple. A mangaka's work, publication history, and on-the-record craft statements are content. Their personal life, politics, and above all their health are not, and speculation about why a series paused is a named hard block in this vertical's rules. The work is the subject; the person is a person. The pen names and self-caricatures many mangaka publish under are part of the record too, a small public face that belongs to the work rather than to the private person.
In use"The mangaka's name on the volume spine is the author credit for the whole series."