Yowai 5000-nen no Soushoku Dragon, Iwarenaki Jaryuu Nintei  

A gentle dragon of 5000 years old, it was recognized as an evil dragon without any cause., 齢5000年の草食ドラゴン、いわれなき邪竜認定

A dragon who has lived for 5000 years was content with its existence until a young girl arrived at its cave. She presented herself as an offering to gain favor for her village. The dragon pretended to be the "Evil Dragon, the Leader of the Demon Lords Army" in order to get rid of her. However, this deception unleashed her hidden abilities, and his peaceful life came to a sudden end.