Ashita Wa Joutenki

あしたは上天気 ; Tomorrow's Weather

From Ultimate Manga Guide: Yaoi comedy about a student, Ikumi Amanume whose part-time job is to cook and do housekeeping chores for his next-door neighbor, Yuuji Touno, a notable scenario writer. Life seems pretty good except for a little problem that Touno-san tends to get too involved in his work and actually lives out the different characters that he creates! So Ikumi's head is kept spinning by the parade of extreme personalities that he encounters, especially when he starts falling in love with the real Touno who, it seems, never hangs around long enough to do anything about his own feelings for Ikumi...