The Blood Lineage of the Heavens

(from ebookjapan):

The year is 1903. Half a year before the start of the Russo-Japanese War, an academic research team from Japan was in Manchuria, near the Korean Peninsula. Their objective was the "King Kota Monument.

The main character of this story, Ryo Azumi, a student at Ichiko High School, was a member of this research team led by Professor Ureshida to study this inscription, which is said to describe the history of the ancient Korean Peninsula and Japan-DPRK relations.

As Azumi, still struggling with his own identity as a nobody, is having doubts about the research itself, the research team is attacked by horse bandits! What will be their fate?