Welcome to the Roadmap for obtaining the platinum trophy for Sekiro: Shadows Die Twice. Unless you back up your Save File, you'll be looking at a minimum of four playthroughs for all of the ending related Trophies. If however, you do back up your save, you're only looking at two playthroughs as there are two cutoff points where you can backup a save.
Step 1 - Reach the Guardian Ape Boss Fight
Play through the game until you reach either the Guardian Ape in the Sunken Valley of the Corrupted Monk at the Ashina Depths. Upon defeating both of these, you'll alter Ashina Castle, voiding many Mini-bosses there and locking you out of a Shinobi Tool if you missed it.
Take the time during this step to ensure you've collected all the [Gourd Seeds] up to that point along with defeating every Mini-boss for their [Prayer Beads]. Also ensure you obtain the Gatehouse Key from the guards on the bridge and use it to open the door to the Loaded Spear in the Ashina Reservoir.
You'll notice the Ashina Castle Idols will become unavailable upon defeating the Guardian Ape and Corruputed Monk. Make your way back to the top of Ashina Castle and when prompted with two dialogue choices with Owl, choose the second, "Break the Iron Code. Stay Loyal to Kuro" to begin the route for three of the four endings.
Step 2 - Follow all Ending Steps and Defeat Sword Saint Isshin Without Speaking to Kuro After
At this point, follow all of the ending steps outlined in the main walkthrough or the pages for the [Return], [Purification] and [Homecoming] endings ensuring that you defeat every Boss and Mini-boss while finding the last of the Gourd Seeds.
- [Gourd Seed Locations]
- [Prayer Bead Locations]
At this point, you should have the Frozen Dragon's Tears (needed for the Homecoming ending) and the Everblossom (needed for the Purification ending) in your possession. Go ahead and defeat the final boss, Sword Saint Isshin, but DO NOT speak to Lord Kuro on the ground after. If you wish to achieve the Platinum in two playthroughs, now is the time to backup your save.
Step 3 - Using Backed Up Saves, Select Each of the Ending Choices
Once your save is backed up, speak with Lord Kuro and choose each of the three choices available to see the respective endings. If you're not backing up your saves, you'll have to reach this point on three separate playthroughs to see all of the endings.
Once given the choice, following the endings, be sure to not head straight into NG+ but instead, stick around. You'll need to make sure that you've defeated all Mini-bosses and gathered the six Lapis Lazuli materials available on each playthrough. Once you're satisfied, head into NG+ by praying at the Idol in the Dilapidated Temple.
Step 4 - Shura Ending and Extra Lapis Lazuli
In NG+, proceed through the game until you reach the top of Ashina Castle for the second time and presented with choices again. Make another backup save here as you'll need to continue from this point after obtaining the Shura Ending. This time, select "Obey the Iron Code, Forsake Kuro" to follow the route for fourth and final Ending, presenting you with two different unique final bosses.
Once defeated and you've seen the ending, reload the save and follow the path for the other three endings so that you gain access to the Fountainhead Palace again. Here you can gain the other four Lapis Lazuli that you're missing in order to complete all of the Shinobi Tool upgrades.
Step 5 - Skill Point Grinding
At this point, all that should be left to you is the Trophy for all the Skills unlocked and this is the most time consuming of all the Trophies. It's worth noting that on each NG+ cycle, you'll obtain more Exp per enemy, this is useful should you find it taking too long to obtain the Exp needed on NG+.