Touhou Mecha: Hell's Rising

Chireiden and Parsia, two territories deep within Gensoukyo's underground, are at war. In order to turn the tide of the war, the hell raven Utsuho Reiuji travels to the Remains of Blazing Hell to attain the power of the sun god Yatagarasu. This power will allow her to use the AM Yatagarasu, a mecha with amazing power. However, the sun god isn't the only thing waiting at the Remains of Blazing Hell...

[From Lemma Soft Forums]