Mitsuhiko 46 years old salaryman who had just been laid off and was told that his wife wanted a divorce, something that he might have been wanting for years visits a soapland brothel. While there slips and hits his head losing consciousness is transported back to his 16 year old body but has retained his memories. Now 16 years old and in high school he meets his first love and classmate Satsuki and his future wife Sachiko. Mitsuhiko believes this is all a dream until he starts realizing that this is no dream. Mitsuhiko decides to start over again anew.

Mitsuhiko (46) now in his 16 year old body flees with Satsuki after being beaten by a couple of delinquents. After parting ways with Satsuki, he makes his way home where he meets his mother, sister and younger brother feeling very nostalgic he starts reminiscing about his current life happy to eat with his family he is reminded of his sad and lonely future. Baba a classmate of his approaches Mitsuhiko wanting to know more about the defeat of the delinquents. Worried about Satsuki's reaction who the one that defended against the delinquents calls calls her up to the roof.

Mitsuhiko who has been attempted to avoid his future wife Sachiko is stopped by her friend Maruo and is questioned if likes Sachiko. Mitsuhiko remembers how his life turned out accidentally voicing his feelings while remembering. After school the delinquents are at the front gate ambushing students passing by. Mitsuhiko attempts to convince Satsuki. He musters up courage and confronts the delinquents.

Mitsuhiko was threaten to bring 100,000 yen, with nobody to turn to he consulted with his sister, Yasuko. Yasuko called her boyfriend Shimotsuma to see if he is able to help. Shimotsuma is a much older man dressed in nice clothing and has an energetic attitude. As they made their way to the meeting spot one of the delinquents threw a glass cup that hit Shimotsuma's forehead.

Mitsuhiko was helped by his sister's boyfriend. The next day Mitsuhiko goes to school and finds that Satsuki is absent. He attempts to find work to pay back the money he had borrowed when he was stopped by a signage that were looking for part time workers. He looks inside to find Satsuki working realizing why she was absent.

Mitsuhiko decided to work at Satsuki's grandmother cafe.On his way home he is intercepted by Shimotsuma, who takes him to a karaoke bar. After being picked up by married woman, Mitsuhiko is reminded of his past life with Sachiko and remembers how "Everyday is boring" and regrets that he never faced Sachiko and spoke to her. At school Bab and Maruo invite Mitsuhiko to a double date with Sachiko, on the other hand Satsuki's grandmother asked him to invite Satsuki to a date.

Ecstatic about his date with Satsuki. Baba asked Mitsuhiko to hang out but turned out to be a double date with Sachiko. He decides to go along with Baba and Maruo's scheme. Despite not wanting to have feelings for Sachiko, Mitsuhiko had a good time. Though with all said and done he feels guilty going on this date knowing he also has a date with Satsuki the following day.

Coming home from his very first date with Satsuki, Mitsuhiko finds his father, Norio who has passed away in his past life, alone at the dinner table eating alone. Mitsuhiko is reminded if life and attempts to change that with this second chance and decides to gather everybody. Sachiko makes an unexpected visit on his day off. Mitsuhiko wonders how their life went wrong to make her think that she was bored in his past life as he saw her having a good time with him. Suddenly he gets a call from Satsuki of an emergency.

Mitsuhiko rushed in support for Satsuki after hearing her grandmother was taken to the hospital. At school he can't help but worry about her at school when she does not come in. Satsuki makes it to school later and Mitsuhiko rushes over to meet her when Sachiko breaks the conversation suddenly.

Mitsuhiko was shocked to hear that Sachiko had a boyfriend. Satsuki noticed his reaction and brought it up to Mitsuhiko. He doesn't know how to go about on how he feels about everything as he watches Sachiko from afar.

Mitsuhiko is beaten by the delinquents after standing up to them protecting Satsuki. Mitsuhiko keeps standing up even after being beaten severely when one of them decide that they've had enough. When Mitsuhiko makes it home he starts having headaches and starts seeing glimpse of his future.

Mitsuhiko wakes up at the hospital. As he regains consciousness he sees his daughter Miyu and his wife Sachiko. Mitsuhiko tries to hug them upon seeing them but he is pushed away by of them as they leave him. Mitsuhiko remembering his time with Satsuki makes a trip to where her grandmother's cafe was only to find out it has since become a paid parking lot.