SD GUNDAM WORLD SANGOKU SOKETSUDEN

Repeated warfare has destroyed countries that once prospered gloriously, leaving the land in ruins. Just when revival is in sight, an epidemic of the mysterious Yellow Zombie Virus breaks out. The virus carriers lose themselves and start attacking people. The survivors are forced to live inside fortified cities for protection. However, behind closed walls, the lord Dong Zhuo has been acting in an outrageous manner since the passing of the previous lord. As if drawn together by destiny, Liu Bei Unicorn Gundam meets Guan Yu Nu Gundam and Zhang Fei God Gundam, and decides to save the world. Eventually, the passion of the three young men will bring about great change in the world. The new heroes unveil a new chapter in history! — Description from AniList community (anilist.co).