Nothing Worth Remembering

Nothing Worth Remembering is a bad ending and one of 25 possible fourth episodes in Shiny Days.

Plot
The plot of Nothing Worth Remembering is identical to From Kotopi to Se-chan up to the point where Makoto drags Setsuna into the Radish to witness Shun and Futaba having sex.

Setsuna flees the Radish after seeing Shun and Futaba and becoming angry at Makoto. Makoto starts to leave as well, believing that his relationship with Setsuna is over. Shun asks if he is Setsuna's boyfriend, but Makoto replies "ex" given what just happened.

Shun tells Makoto that he needs to talk to him, but reconsiders that maybe he should chase after her, or he may never win her heart back. Makoto says he doesn't care anymore, and Shun asks him to walk with him. They go to the beach, where Shun talks about his history at the restaurant. Makoto grows impatient and says he doesn't really care, but Shun claims that he's got plenty of time to listen, as he'll never catch Setsuna at this point anyways.

Shun tells Makoto about Setsuna and how she has always put the happiness of others first, even if it meant being unhappy herself, and cites Sekai as an example. The only thing Setsuna has ever done for herself is take the nickname "Se-chan." The name would have worked for Sekai as well, but Setsuna wanted it for herself and asked Youko, Mai, and Shun to let her have it. Makoto is confused why Shun would have had a say in the matter, and it suddenly dawns on him that Shun is Setsuna's father.

Makoto asks why he was with Futaba if he's Setsuna's father, and Shun says that his life has been a long series of mistakes that drove Setsuna away, and as a result he's not allowed to call her Se-chan anymore, as the nickname is reserved only for those she truly cares about. Makoto's opinion of Shun softens, and he apologizes, but Shun says the fault is his.

Makoto says he still believes in her and resolves to go after her and regain her trust. He begins to run, thinking to himself that he knows she still likes him, and that he wants to start over with her. He arrives at the tetrapods where they had spent a lot of time over the past weeks, but she isn't there. Confused and crushed, Makoto cries out.

Explanation
Nothing Worth Remembering is a fairly confusing ending if taken at face value. Its meaning is hidden in Makoto's perception of Setsuna. Getting this ending requires his affection for her to be lower than it would be for From Kotopi to Se-chan, and as a result, Makoto's belief in Setsuna is centered around how she feels about him moreso than how he feels about her; notably, he believes that she truly loves him. As a result, he (somewhat arrogantly) thinks that she wouldn't leave him so abruptly and goes to the place that had special meaning to them both during the summer: the tetrapods near the beach, where they spent many hours in conversation. He arrives and finds her not there, revealing to Makoto just how wrong he was.

Route
The route for Nothing Worth Remembering stems from 33322 and is an available ending regardless of which variant of the lower branch is taken. To get this ending, the bar must be even lower than the requirement to get How Many Hours By Train?

If the bar is somewhat higher when Setsuna flees, you will get the ending How Many Hours By Train? instead.

If the bar is significantly higher when Setsuna flees, you will get either From Kotopi to Se-chan or Together instead, depending on whether episode 2 was Part-time Job or Drowning in Secrets.

The exact bar thresholds that differentiate Nothing Worth Remembering, How Many Hours By Train?, and From Kotopi to Se-chan/Together are hard to quantify, so it may take some experimentation to get the ending you want. Luckily, there are plenty of opportunities to move the bar prior to Setsuna's flight to Paris.