If you're looking for manga similar to Love, Chunibyo & Other Delusions! Heart Throb: The Rikka Wars, you might like these titles.
Entarou Hakujou - ‘the matchmaker who makes unmarriable people marriable’. As always, he is busy again today supporting his clients as they pursue their common goal: marriage! However, the members of Hakujou Marriage Agency are all a little “odd”, and facing various struggles as they search for their perfect partners.
Yuuto Kyoubashi, a light novel illustrator with a particular fetish for navels. He meets Nonoka Nogi, a 14-year-old cosplayer, who is his fan, and she begins helping him out with his housework. The story shows Yuuto and his colleagues, which include his editor and other light novel and adult game illustrators.