Diego no Kyojin

is a Japanese light novel series written by Satoshi Wagahara, with illustrations by Kurogin. The series began publication on November 10, 2016 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
An era of change that is exciting to discover a new continent. Diego, a young man living in the Kingdom of Spinea, a maritime nation, was studying the illegal onmyodo technique. As a result, he is attacked by a mysterious daughter who doubts the source of power, and even the Holy Church is noticed. Diego decides to board a ship of the New World Expeditionary Force with his rotten friend Alvaro.

A new continent where a large golden tree rises and a giant protects the forest. What was waiting for them was Rera, a girl trapped in a water cage. At the command of Captain Hoakin of the Expeditionary Force, Diego seeks a way to get the girl out of the cage using Yin and Yang techniques. However, with Rera's awakening, her daughter Rosen, who has attacked with Spinea, appears. She drives the forest giant "Tankamui". Diego will be involved in a great battle between the maritime nation and the indigenous peoples.