Hakaima Sadamitsu (2001)

Sadamitsu, a high-school delinguents turned to a masked-hero, while not dealing with his rocky relationship with the strong female protagonist, he puts on a motorcycle-helmet-like mask and becomes a semi-robotic superhero who fights. He is assisted by other possibly- mechanical creatures in order to save the earth from the invasion of 20,000,000 escaped alien convicts. (Source: AniDB)