A Wild Sheep Chase

Fantastical and whimsical Japanese translated prose.  Very quirky, but towards the end, its the sort of book you have to keep reading.  The protagonist is a not particularly ambitious, but stubborn, man with a small copy agency.  Some VERY weird things happen to him after designing a newsletter with an odd image of a sheep, and he spends several weeks with his equally strange girlfriend on a "wild sheep chase", including encountering a man who dresses as a sheep.