A long while ago, lay a facility deep within a jungle, stationed nearby a waterfall... One dedicated to discovering the secret behind eternal life.
Unfortunately, the facility's means of research were far from what you'd define as... ethical. So, its journey came to a roadblock, as their research was shut down.

Nowadays, the lab walls of the abandoned facility have been dilapidated beyond recognition, and nature has retaken it as its own.
However, rumor has it, that despite continuing their research would be illegal, deep within the facility, the director behind the program carried on with their work regardless...

Recently, strange noises have been coming from the empty walls of the supposed abandoned Eternus Institute, and Mega Man has been sent to investigate!
But little did he know what he'd discover within...