Nioh is a super-hard Action RPG out of Japan that has a multiplayer, but it's one generally more focused on summoning random strangers into your world than pairing up with your friends. Stop me if this all sounds massively familiar. Well, yeah - I can stop right away if you've played Dark Souls. The system from there, which is great, has been by and large borrowed for Nioh, though Koei Tecmo's samurai slasher takes some liberties and new directions all its own.
Summoning in Nioh is handled via an item called Ochoko Cups - basically, these items are what you use to encourage another wayward soul to land themselves in the deadly world of your save file. There's a catch, however: Ochoko Cups are fairly limited items, and if you want to co-op a lot, you'll need to have a lot of them. That we can help you with.
Getting Ochoko Cups for Coop Play
First thing's first - it makes most sense to talk about the simple and natural way to get your hands on Ochoko Cups, and that's through completing side missions. Ochoko Cups are fairly frequently offered as rewards for some of Nioh's side content.
The easiest way to find out where to spend your time is to use the pre-mission map screen. View the mission information, since each lists a bunch about that mission including, crucially, a list of rewards and boons for completing it. Look for a mission with an Ochoko Cup as a reward and head on in - but in this you of course have to take on a new mission, so it isn't all rainbows and peace on earth, but rather quite the opposite.
Rarely you might also find Ochoko Cups out in the world in chests, too. While it goes without saying in any RPG, be fastidious and open every chest, for you never know when some Ochoko Cups will be inside. To kick off a co-op session, simply use the cup when in an area. There is another method to get cups... see that below.
Farming for Ochoko Cups by battling Revenants
Another concept that'll be familiar to Dark Souls players are the basic idea of Revenants - the ghosts of others who have failed in their quest. Revenants are marked in the world not with bloodstains but with graves with swords sticking out of them. Some graves are part of the actual designed game world, while others are randomly generated for you based on the death location of other real-world, online-connected players. For the purposes of this guide, both function identically.
Here's the deal: Ochoko Cups are still a rare drop off Revenants, but battling these guys is by far and away the most reliable and likely method to get yourself more Ochoko Cups. Battle the dead warriors and defeat them and you'll get a cup. The higher level a Revenant is the higher the chance appears to be to get your hands on an Ochoko Cup, too, so you want to push your luck and try to battle those more powerful than you.
When you approach a grave to summon, pay attention to the information offered to you by the game. It'll tell you the level, their equipment, how they died - all vital information. You need to use this information to work out if it's a fight you can win. Try to find Revenants as high a level above you as possible that are still beatable. Fight them, kill them, and hopefully, if you're lucky, an Ochoko Cup will be among their drops and you'll be on for some more co-op play. Fingers crossed.