In total there are four different endings for Sekiro which depend on some choices that you make throughout your journey. If you want to unlock each of Sekiro's endings, you'll need to know what to answer for those decisions when they come, so let's find out how to get each ending for Sekiro. There's obviously going to be a few spoilers here, but we'll try and keep it abstract so you can just find out which choices to pick if you still want a few surprises.
How to get the Shura ending
Your first chance to end the game comes with the Shura ending. After beating Guardian Ape and the Corrupted Monk, head back to Ashina Castle. Meet up with Owl on the roof and when you're given the choice between him and Kuro, choose Owl. Then two boss fights are unlocked which you'll need to beat if you want the Man Without Equal achievement.
How to get the Immortal Severance ending
When you need to choose between Owl and Kuro, choose Kuro. Carry on with the game as normal but do not go back to Hirata Estates.
How to get the Purification ending
On the Ashina Castle rooftop choose Kuro again, then go to Isshin's tower and you'll be able to eavesdrop on a conversation between him and Emma. Then go back to Kuro and eavesdrop on him, head to the corner of the room for the prompt. Head to an idol and rest, then talk to Emma and agree with her. Rest at the idol again and talk to Emma again. Travel to the Old Grave idol to talk to Emma there, then head back to the Dilapidated Temple and eavesdrop on Emma and The Sculptor. Talk to Emma to receive a bell to use at the Buddha statue.
Now, in the Hirata Estate, defeat two new mini-bosses and head to Lady Butterfly's room. Beat the new boss in there and then carry on with the game as normal.
How to get the Return ending
Again on Ashina Castle's roof choose Kuro. This time head to the Temple Grounds idol and have Sekiro dive underwater into the pond to get the Holy Tome: Infested scroll (and don't forget the Prayer Bead). You can also obtain the Holy Tome: Infested if you visit Senpou Temple's Main Hall before killing Genichiro. In this case, speak with the monk here until he gives you the tome and asks you to present it to the Divine Child. Enter the Inner Sanctum to talk to the Divine Child and hand her the soggy scroll you just dredged up. Eat the rice she gives you, then rest at an idol. Talk to her again and keep eating that rice (you gotta get your strength back after all). Continue to do this until she asks you for a Persimmon at which point hand it over, then keep eating the rice. Eventually she'll give you some rice but it's for Kuro. DO NOT EAT KURO'S RICE. Go give the rice to Kuro.
Once you've fed Kuro, go back to the Inner Sanctum and talk to this rice-happy kid one last time then leave. She won't be there anymore so you need to head to the Hall of Illusion to talk to her in front of the Great Tree. The scroll she wants this time is in the cave just to the left of where you rang the bell to get into this bit. Give her the scroll, then you'll need to give her two Serpent Fruits. The "Fruits" are in fact Serpent Viscera which you'll get from the Giant Serpents.
To get the Fresh Serpent Fruit, go to Senpou Temple's first idol and drop to the right of it. Use Puppeteer Ninjutsu on the kite enemy to make him use it for you. Go down the path and use the kite to grapple to the next area to find a Giant Serpent. Kill him for the Fresh Serpent Viscera "Fruit".
To get the Dried Serpent Fruit, go to Bodhisattva Valley and follow the river away from where the Guardian Ape boss fight happens. There's a cave with the other Giant Serpent in it close to the Toxic Memorial Mob merchant. Make your way through the inside past the lizards and wall enemies until you reach the snake. From here you'll need to use the Ninjutsu Puppeteer Technique on a nearby monkey (follow our guide to be sure) to distract the Serpent while you run through the door it's guarding, Grab the Dried Serpent Viscera "Fruit" from inside.
With both Serpent Fruits in hand, go back to the Divine Child at the Inner Sanctum to hand them over. Once you have, rest at an idol then talk to her again to receive Frozen Tears. Now carry on with the game as normal. At the end, give Kuro the Frozen Tears.
Right, now you know how to get all the endings in Sekiro. Which one have you chosen as canon?