Where is the cut-off point for the Dragon's Homecoming Ending?

The Dragon's Homecoming Ending is the most convoluted of all the Sekiro Endings, requiring multiple interactions with all characters, to get specific items in a particular order, so that you have everything you need for the choice after the final boss battle.

The part I'm having trouble with is keeping track of when the cut-off points are for the interactions with Kuro (eavesdropping) and Emma to track down the appropriate information in order to gain access to the Frozen Tears item. For example, in my current playthrough I have completed the Sacred Realm area (Fountainhead Palace, and defeated the Sakura Dragon), I have all the Shinobi tools (though not all upgraded), I have received the rice balls from Kuro, but I have not done anything to gain access to the "investigation" with Emma, or eavesdropped on Kuro yet.

What is the trigger/point of no return for this side-quest to achieve this ending?

sekiro-shadows-die-twice

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How do you get the Dragons return ending?

Head through the game to the final boss fight, and you'll get an option to use both the Divine Dragon Tears and the Frozen Tears on Kuro. This will unlock the Return ending, where Sekiro and the Divine Child (who is cradling severed Kuro) travel to the West to find the birthplace of the Divine Dragon.

What happens if you obey the iron code?

Obeying the Iron Code in Sekiro If you choose to obey and forsake Kuro, this will trigger a final boss fight, and you'll get the Shura ending once you get past it. However, it's worth noting that this seems to be regarded as the 'bad' ending in Sekiro. You'll be able to start new game plus after this, though.

How do you get the immortal severance ending?

Ending 2: Immortal Severance

Obtain the Mortal Blade, Lotus of the Palace and Shelter Stone.

Disobey with Owl, breaking the Iron Code.

Defeat the Divine Dragon and obtain its tears.

Defeat Genichiro Ashina and Isshin, the Sword Saint.

Choose to give Kuro the Divine Dragon's Tears.

What is the best ending for Kuro?

Defeat the final boss, then give Lord Kuro the Dragon's Tears and Frozen Tears to end the game.

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Images: Ketut Subiyanto, Tom Fisk, Enoch Patro, Katerina Holmes