Ruten no Terma

Tokumaru Tokuda is a medical student who is taking a leave of absence from school and spending every day lazily. To search for his big brother who went missing after sending an e-mail saying "Help me," Tokumaru ends up going to "Western Tibet." Using the photo that his brother sent as a hint, Tokumaru and two male guides, Sonam and Namgyal head toward a certain valley. However, it's a valley that not even the locals go near since it is said that the valley brings disaster on anybody that comes near… The three men embark on their long journey on foot in Western Tibet, the land high above the world.

(Source: Manga Box)