The correct way to sort out the characters from the one that knows more to the one that knows less is the following:
1. Takehito; 2. Tajomaru; 3. Masago; 4. the woodcutter; 5. the informer; 6. the buddhist monk; 7. the old woman.
Step-by-step explanation:
The 3 main characters are: Tajomaru, the assailant; Takehito, the husband; Masago, the wife of Takehito.
The three of them (Takehito using the voice of a witch) know what happened and when they tell the story accept basically the same: Masago was raped by Tajomaru in front of Takehito, while he was tied to a tree; then Masago scapes and Tajomaru goes away. How Takehito dies is not clear, as the three versions are different.
Now, as Takehito is already dead and he has nothing to lose or prove to others, then he uses the voice of a witch to clarify what happened, and therefore is the one that not only knows what happened but also tells it as it really was. Also, as he killed himself, then he was alive while the others left, and he actually knew all the details of the story.
The second one to know more is Tajomaru, and the third is Masago, because Masago rans away first and she actually doesn't know who killed his husband even when she said she was the killer; after Masago left, Tajomaru took his turn, leaving Takehito alone in the woods, even when he said he was the killer. Both tried to dignify their place in the story, but they both lied.
On the other hand, the 4 supporting roles on the story are: The old woman, Masago's mother; the woodcutter, who found Takehito's dead body; the informer, who caught Tajomaru; and the buddhist monk, who met Takehito and his wife right before the incident.
The fourth person that have more information about the incident is the woodcutter, because as he found the body he knew that Takehito died by a fist stuck in the chest and he could make assumptions and nothing else about who was the killer, but he didn't know more about what happened.
Then, we have the informer because he knew almost everything about Tajomaru, and gave some assumptions about the incident and about what happened to Masago. But he was not in the place where Takehito died, so he only knew about the context of the assailant but didn't know about the event itself.
The next one is the buddhist monk because, even if he didn't know anything about the incident nor about Masago's characteristics, he gave information of Takehito's belongings before the incident, which is helpful for the officer to make a case.
The one that didn't know anything about the incident, and only gave information about the normal lives of Takehito and Masago, but that didn't help to make a case, is the story of the old woman, that happens to be Masago's mom.