Reunited as adults, two childhood friends fall madly in love and won't let anything - not even death - tear them apart, in this supernatural love story.

Soma Yui and Torino Naoki were childhood friends, but they met again as adults. Just as he decides to propose to Yui, Naoki suddenly disappears from Yui's sight after being embroiled in a mysterious incident. Naoki continues to wander in this world as a spirit without knowing that he has died. Naoki asks Uozumi Yuzuru, a detective who is the only one able to see Naoki, to convey his feelings to Yui, but Naoki ends up breaking up without properly saying "thank you, goodbye, and I love you" to the person he loves the most.—MyDramaList

When Yui Soma (Mao Inoue) and Naoki Torino (Takeru Satoh) were children, they were friends, but eventually lost contact. They meet once again as adults and they fall in love with each other. Naoki Torino decides to propose to Yui Soma, but he gets involved in a mysterious case and dies. Yui Soma is unaware that Naoki Torino has died and falls into despair due to his sudden disappearance. She tries to find him again. Meanwhile, Naoki Torino is not aware that he has died. His spirt wanders around and he tries to make contact with Yui Soma, but it seems she is unable to hear or feel his presence. Detective Yuzuru Uozumi (Kenichi Matsuyama) appears in front of Naoki Torino. Apparently, Yuzuru Uozumi is the only one who is aware of Naoki Torino's spirit. Naoki Torino would like Yuzuru Uozumi to convey a message to Yui Soma.—AsianWiki

When childhood friends Yui and Naoki are by chance reunited as adults, they begin to feel they were destined for each other. However, just as Naoki prepares to propose to Yui, he becomes embroiled in a mysterious incident and dies. Now Naoki's soul wanders the world unable to express his true feelings for Yui. Yuzuru, a detective and the only person who can see Naoki, goes in pursuit of the truth behind Naoki's death. At Naoki tries to use Yuzuru to talk to Yui, but will he be able to convey his message of love?—Japan Program Catalog

"Why Didn't I Tell You a Million Times?", also known as "100 mankai Ieba Yokatta" is a 2023 Japanese television series starring Mao Inoue, Takeru Satoh, and Kenichi Matsuyama. When childhood friends Yui and Naoki are by chance reunited as adults, they begin to feel they were destined for each other. However, just as Naoki prepares to propose to Yui, he becomes embroiled in a mysterious incident and dies.