Nihon e Youkoso Elf-san.

Kitase Kazuhiro is an ordinary salary man who always leaves the office on time. Though this is Japan, so perhaps he's not really ordinary after all. What's truly strange comes after that; Every night, he takes a shower, changes into his pajamas and has a good night's sleep. Then he dreams of a fantasy world, and only wakes up when he dies or sleeps in that world. One day, he's killed together with his elf friend, after stumbling onto a dragon's lair. "A nightmare," he sulks, until he finds his elf friend in his bed.

(Source:MU)