Okay, so the recap so far:
(Future chapters, implied in 1st chapter)
Naomi Konno killed her mother at the age of 11 after repeated abuse, and to protect her bird pet.
(Chapter 1)
She met the lecturer, and drew the first drawing in the first chapter. A drawing of a house without door, and a tree with her pet inside it.
Later, she married Yoshiharu Miura who worked as an art teacher in a high school.
(??) Might worked as a midwife.
Has a son, Takeshi Miura.
[1992] (Chapter 9 flashback)
Yoshiharu Miura's murder
(??) Unknown if Yoshiharu abused his son, and wife, or it's just Naomi's paranoia, she killed her husband.
There are three suspects, Yoshiharu's wife (Naomi), his student (Yuki Kameido), and his friend (Nobuo Toyokawa).
After the incident, Yuki would visit Naomi, and Takeshi to take care of them.
[1995] (Chapter 9)
Isamu Kumai, a newspaper reporter, tutored Shunsuke Iwata, a former Yoshiharu's student, under him.
Iwata then interviewed Yuki Kameido, and learn that she had a crush on Yoshiharu.
From the interview, Iwata found a silver lining.
Chapter 13~14)
Iwata managed to unveiled Naomi's murder trick, and got killed by her.
(??) Yuki might told Naomi that a reporter (Iwata) interviewed her, and he said that he had a breakthrough. That's how Naomi knew Iwata is dangerously close to the truth, and moved to kill him.
The other suspect, Yoshiharu's friend, Nobuo Toyokawa, was found dead. Assumed as suicide.
[2007]
Yuki Kameido married her teacher's son, and also a childhood friend, Takeshi Miura (Now use the name Konno), and live together with Naomi.
[2008] (Blog entries, Chapter 1~3)
Takeshi Konno made a blog, under the pseudonym of Nanashino Ren.
For some reason never mentioned his mother directly in the blog.
[2009] (Blog entries, Chapter 1~3)
(??) Yuki might later realize that Naomi is the killer of her favorite teacher. Knowing this, Naomi might threatened Yuki, or even planning to make Yuki die during childbirth.
Yuki then started to draw hints for her husband, so he can know the truth.
(*The entry about Yuki sudden cry, and start drawing is just one day apart.)
Yuki died, but her son, Yuuta survived.
[2012] (Blog entries, Chapter 1)
Takeshi later solved his wife's drawing.
(??) Concluded that his mother is responsible for his wife's death.
Announced to stop blogging, deleting many entries between the announcement, and Yuki's death entry.
Takeshi died.
[2014]
(Chapter 1 starts)
Kurihara, our eccentric friend from Hen na Ie, found the blog and started to investigate about it along with his friend, Sasaki.
[2015]
(Chapter 4~8 starts), (Chapter 15)
Naomi now live with Yuuta after Takeshi's death.
Isamu Kumai, now a retired reporter, found Naomi's apartment, and tried to make her confide.
Naomi is jailed for assaulting Kumai.
I thought so too until this chapter. The similarities are too much if they're a different person, especially that bird. I guess the artist just drew the lecturer looking too young. The lecturer did say that when she was managing Naomi she had just started her career, so maybe she was still young at the time.
Yup. Other than the bird, the girl's outfit is exactly the same. As for the lecturer's appearance, well, Naomi is also wearing thick make up to hide her true age. Maybe that's the theme.