The memory-finding mission in "Dynasty Warriors: Origins" is a unique mission in the game. If you want to do this mission, you can do it in Chapter 3. You will meet Yuan Hua in Night City. Yuan Hua is a young doctor who is very interested in Ronin's amnesia and vows to help him.
How to do the memory search mission in Dynasty Warriors Origins
When you enter the main plot of Chapter 3, you will meet Yuan Hua in Night City. Yuan Hua is a young doctor who is very interested in Ronin's amnesia and vows to help him. After interacting with Yuan Hua, the "Looking for Memory" side task will be automatically unlocked, and you can complete this task when you have time. The task requires you to collect the following herbs in the wild.
Light Vanilla
Moon Vanilla
Wood Vanilla
Red Vanilla
Herbaceous Li
At the beginning of the mission, you will only be given one objective, which requires you to find an herb. Once completed, talk to Yuan Hua and give him the herb and you will get your next objective. You'll also receive a reward each time you turn in an herb.
When you hand over all the herbs to Yuan Hua, and finally to Li Herb, he will ask you to wait for a while until he completes the preparation of the potion. During this period, you can continue to complete the plot of Chapters 3 and 4 until near the end of Chapter 4. Towards the end of Chapter 4, you will be asked to return to the village and collect some cherry blossoms. After a cutscene, Ronin will learn about his past, after which you'll unlock Unparalleled Rage. This ability allows Ronin to use the Ultimate Musou attack during combat, and once this ability is unlocked, the side mission will end.