Mega Man X - The Day of Sigma is a oVA anime that premiered in fall 2005, produced by Xebec.

About the production: the story comes from a video game, there is 1 episode of about 30 minutes and its current status is "finished".

Its main genres are action, mecha and sci-fi.

On AniList, Mega Man X - The Day of Sigma has an average score of 68%, a good score, and appears on 3,111 users' lists.

The year is 21XX. Reploids are commonplace now, after Dr. Cain rediscovered Dr. Light's old lab and based several designs off of Dr.Light's original, called "Megaman X." X, meanwhile, has joined the Maverick Hunters, and works with unit leader Zero under the command of General Sigma. It is their job to terminate rogue reploids, those who have become violent. (Source: Anime News Network)

Official synopsis from AniList.