N no Tame ni (2014)

Also starring Eikura Nana. N no Tame ni is a story on the journey to seek the truth of a murder case that happened 10 years ago with each of the party involved holding on to their own dark secrets.

Similarities:
1) Both are about mystery with flashback storyline.
2) Strong romance involved.
3) Both are about the pursuit of a certain name/people

The team behind those 2 dramas is almost the same, and you can feel it in the atmosphere, writing and direction !

Sakuragi Shun is a salesman who works for a Sunbath Home Housing, a house manufacturing company. He enjoys a happy life at home with his wife and daughter. Due to a sudden personnel change, he was assigned to transfer to Kagoshima, a city he was familiar with from his junior high school days. There, for the first time in 17 years, he is reunited with his first love Takeda Hana. She works as a junior high school teacher, while her husband who works as first mate, spends most of the year at sea, so she usually lives alone. While reminiscing the bittersweet memories of their high school days together, a hidden Pandora's box begins to open...

Furthermore, sparks also fly with Katoyama Naoya, Shun's friend and former love rival from their junior high school days, who now works for another company in the same industry. Although Shun has a beloved wife, the flames of jealousy quietly flare up. Meanwhile, Sakuragi Shun's wife is trying to suppress her anxiety. Based on their phone calls and emails, she becomes suspicious that her husband is cheating on her, and in order to eliminate her fears, she takes a trip to visit him in Kagoshima. As the slight lies begin to pile up, the truth becomes complicated, and when the lies are exposed, how will the relationship between the four of them
change?

Both series have flashbacks from the past and a range of mysteries, which involve multiple characters and someone's death.

Investigations on a mysterious woman Toko started when Sonoe, a teacher and Toko's fellow faculty member, was found dead as a result of what seemed to be an unfortunate accident. Eiki, an insurance investigator, and Takeshi, an ambitious police detective, find links between this case and the deaths of Toko's 3 fiances, and are determined to uncover the truth.