Konami announced a few months ago that it was partnering with Capcom to put some of the Monster Hunter monsters into Metal Gear: Peace Walker so that Snake could test his skills. These stages would be in the form of unlockable missions. However, if you were just casually playing through Metal Gear Solid: Peace Walker, you could easily miss these gems. Get ready to find Rathalos and other famous Monster Hunter err monsters!
How to Unlock Monster Hunter Missions in Metal Gear Solid Peace Walker? Read on to find out!
Step1: Listen to Chico
The first piece of the puzzle is that you have to listen to every one of Chico’s audio briefings. To do this, pick a mission, select “Briefing Files” before deploying, and then move to the Chico file library. Listen to each one of these tapes – or at least use the circle button and click through every line of dialogue so that he exclamation icon marking it new disappears.
Step 2: Blow the Load
Now that you’ve listened to Chico ramble on and on about monsters, head over to Extra Ops and go out on  Item Capture. This is a seemingly simple mission. Go in, take care of the three guards, and blow up the item crate. However, there’s more to it than that if you want Capcom’s content.
After you blow up the crate, collect the items but do not head to the extraction point. Instead, head south to the beach at Playa del Alba. When you enter, take a left and head down the dock. Miller will radio in that there’s a “weird looking animal” over there.
Step 3: Chat with Trenya the Cat
Run down the dock, and you’ll meet Trenya, a talking cat from the Monster Hunter universe. Snake and the kitty will make some perrrrrfect puns, and the mission will end.
Step 4: Monstrous Mission
Scroll to the end (or what should be the end) of your Extra Ops, and you’ll now find  Hunting Quest: Rathalos. This is your very first Monster Hunter quest. Hooray. If you can beat this flying beast, you’ll unlock extra quests to go forth and conquer.