Honnouji kara Hajimeru Nobunaga to no Tenka Touitsu

Honnouji kara Hajimeru Nobunaga to no Tenka Touitsu summary:

Makoto Kurosaka, a high school student visiting Kyoto on a school excursion, decides to go to a temple to see a Buddhist statue that is being displayed for the first time in 450 years. However, as he navigates the pitch-dark underground passageway of the temple hall, he gets separated from his friends and somehow manages to escape the darkness, only to find himself in the middle of the "Honnoji Incident" in the Sengoku Period! After saving Nobunaga Oda from a tight spot, Makoto becomes a guest of the Oda family and helps Nobunaga unify the country. Use your knowledge of history to rise in the Warring States period!