On to Chapter 40.
I looked like I might start crying at any moment too.
It’s been a year since we broke up without even saying goodbye.
A year since I cut off contact without warning.
A year since I dumped him without giving any reason.
Even though I was the one who treated him so horribly, so one-sidedly…
Why is it, why is it that all these intense feelings are bubbling up now?
Why do I find myself wanting to run to him and throw myself into his arms?
So Yami admits to herself that she still has feelings for Yuu and wants to run into his arms. Keep in mind she's already acknowledged to herself a chapter ago that she knows Hikari's plan is to confess to Yuu and that she believes it will go well.
Yuu: “What? Why? Isn’t this… Hikari’s classroom…?”
Yami: “…”
But—
The moment that name, Hikari, came up…
My face twisted into a full-blown, sarcastic grin.
Yami: “…It’s been a while, Taa-kun…?”
Yuu: “Huh…?”
Teasing that openly confused look on Yuu’s face—
And as if trying to swallow the words:
Yami: "That’s your first reaction to seeing me again after all this time?!"
So, she's angry that the first thing Yuu does is mention Hikari.
Yuu: “I was seriously worried, you know. When you suddenly stopped contacting me a year ago…”
Yami: “Well, I got bored. Of you, Yuu.”
Yuu: “…I… I see…”
Yami: “Exactly. So drop it already.”
Yuu: “Y-yeah. Got it. Sorry.”
Yami: “…”
Don’t believe that so easily, you idiot.
Don’t act all hurt on your own, you idiot.
Is that really what you think I’m like?
Or are you just trying to believe what’s easiest to accept?
Yuu: “S-speaking of which… if you’re back in school, then your parents…”
Yami: “Ahh, if you mean my dad, that’s all been dealt with… That side of things is fine now.”
Yuu: “I see… that’s good.”
Good? No, it’s not.
Pick up on the nuance, for once.
My mom’s issues are still completely unresolved.
Why is it that Yuu always lets go of my hand at the most important moments? Idiot.
She's berating Yuu for not reading between the lines when (as far as we can tell given the minimal Yuu POVs - he's shown no indication of ever reading between the lines). She even says "Pick up on the nuance, for once" which implies that previously, Yuu had not ever picked up on any nuance Yami was giving.
She's thinking Yuu always lets go at the most important moments. This is a key phrase that I'll bring up later.
Yami: “So, what about you? How have you been lately?”
Yuu: “Me? Nothing much has changed.”
Yami: “Well, your girlfriend has.”
Yuu: “We’re not exactly dating yet…”
Yami: “Yet, huh…”
Yuu: “N-no, uh… Let’s just drop this topic too, okay?”
Why?
Why can’t I ask, Yuu?
Do you seriously think I don’t care anymore?
Do you really expect me to smile and say,
‘I’m rooting for you and Hikari, as your friend~’?
…What the hell, me.
My head’s a mess, bouncing all over the place.
This is my first time talking to Yuu in a year, and my words and thoughts are completely out of sync.
She gets mad again when the topic of Hikari comes up. She gets mad when Yuu doesn't want to talk about Hikari. She's getting mad at the thought that she thinks Yuu expects her to root for him and Hikari when he hasn't even said anything about that. She's making up reasons in her head to get angry when just one chapter ago she was telling herself that Hikari was going to confess to Yuu and it would turn out well. Seems to me like she's not buying what she's trying to sell.
Do I want to lash out at him?
Do I want to talk about Hikari?
Do I want to reminisce about me and Yuu?
Do I want to interrogate him about Hikari and Yuu?
Besides, Yuu hasn’t done anything wrong.
I know that better than anyone.
He’s kind, sort of cute, a little too easy to sway…
But that time, I was the one who nudged him in that direction.
So I can’t. I can’t go any further than this.
I can’t tie him down.
Not to this place.
Not to me.
She internalizes that Yuu hasn't done anything wrong but just previously she was talking about how what she's feeling and what she's saying are out of sync. While she hasn't said anything about that topic yet, you could infer that if her feelings and words are out of sync then her thought that Yuu hasn't done anything wrong would imply that actually he has but she hasn't said that yet. She mentions that Yuu is a little too easy to sway, again making a reference to how she could manipulate him as she did to Haru and Yuki earlier. Finally, we get Yami mentioning she can't tie Yuu down - does she mean this truly or is this another instance of her thoughts and actions/words being opposite so what she truly wants is to keep Yuu to herself?
Yami: “Go on, Yuu.”
Yuu: “But…”
Yami: “What, you’re gonna break your promise to your girlfriend?”
Yuu hesitated for a moment, showing a trace of indecision.
But in the end, he reached the “obvious” conclusion and gave me a regretful look.
Yami thinks it's obvious that Yuu would go for Hikari and not her. I believe something is brewing up inside Yami.
Yuu: “I still think about you all the time, Yami-senpai. Of course I do.”
But—
But the moment he said that,
Just for that one moment—he had the face of a real guy.
The face Yuu had when I was head over heels for him.
Yami: “Go.”
Yuu: “…Yeah.”
That’s why I hurried Yuu along.
Because I didn’t want him to see.
To see my lingering feelings.
Yami is admitting to herself that she still loves Yuu but she's trying to get him to leave so she doesn't hurt Hikari - at least that appears to be what Yami's thinking at this moment.
Yuu: “Okay then, Yami-senpai, see you—”
Yami: “...!”
How could he—
Even though I’m in such a rush.
Yuu slowly turned to me with a smile once more.
And yet, and yet...
He turned his back to me and started walking away.
One step, two steps...
Yuu was moving away from me.
Leaving me forever.
Yuu's doing what Yami asked but she's pissed off that he would "dare" to say "see you" when she's trying to cut him out of her life completely to make things easier for Hikari. She's also mad that Yuu's walking away. I mentioned earlier that Yami thought Yuu always lets go at the most important moments and here he is doing it again. It's at this moment that Yami starts to unravel.
Yami: “...What, are you trying to turn this into a memory or something, Yuu?”
Yuu: “Huh...?”
What the hell am I saying?
I’m the one who told him to leave.
I’m the one who said, make it a memory.
Yami: “You ignored me for an entire year... And now what? You want to part ways cleanly, like it’s some beautiful, bittersweet goodbye?”
Yuu: “Yami... senpai?”
What am I doing... What am I doing...
This is such a messed up grudge I’m throwing at him.
Yami: “You could’ve found me, Yuu... You knew I was going to the same school as Hikari, didn’t you?”
This is completely my fault—only mine.
Yami: “Even if I blocked your calls, it wouldn’t have been hard to find me.”
No doubt about it. I’m the one who was in the wrong. I’m the one being ugly.
Yami: “And yet... and yet... You never even tried to find me...!”
Anyone listening would think this was absurd, totally irrational.
Yami: “I’ve been going to school since last September, you know?”
Of course he wouldn’t have known that.
He wasn’t responsible for any of it.
Yami: “If you’d skipped school just once... If you’d waited in front of the station in the morning... If you’d found me and called out to me...”
That kind of thing—There’s no way you could’ve done it. It’s not realistic.
Yami: “And even if you had, I would’ve run away for sure. Even if you caught me, I would’ve pushed you away.”
In fact, if you had done all that, it’d be stalker behavior. Anyone would be creeped out.
Yami: “But still—if you had kept trying, if you had chased me down again and again—!”
But I’m not normal.
There’s something wrong with me.
That’s what I wanted you to do.
And I hated that you didn’t.
Yami: “If you had, then in the very end, I would’ve dropped everything, let go of it all, and run straight into your arms!”
Yuu: “...!”
My raised hand struck Yuu’s cheek with a dry smack.
He had come back—
Even though he had walked away, he was now right in front of me again.
Because he’d returned to be blamed, to be yelled at.
Yuu: “Yami-senpai, I—”
Yami: “Shut up! Don’t act like you know anything, Yuu!”
Yami admits that what she's saying is irrational but she mentioned earlier that Yuu is a little too easy to sway. Right at the end she mentions that even though Yuu had walked away, now he was right in front of her again. Even though Yami admits she's hitting him with a messed up grudge it still allowed her to get him to come back instead of immediately going to Hikari.
Ugh... That’s why I was hiding.
Ever since he came to our school—into my classroom—I kept sneaking out.
So why, why... did I come back?
Why did you find me again, Yuu...?
Why did she go back? I think part of her deep down felt there was a chance she'd run into Yuu if she went to the classroom and since self-destruction is part of Yami's kit she went that route.
Yami: “Come to think of it, you didn’t say it last year... did you?”
Yuu is crying.
I'm crying too.
Yami: “Goodbye, Yuu.”
Yuu: “There’s a limit to how cowardly you can be, you know...!”
But Hikari... wouldn’t understand.
She was hiding behind the door, and couldn’t see our faces.
Here we get some damning information. Yami, being the one to ghost Yuu, knowingly points out that Yuu didn't say goodbye last year. She knew he still had some feelings for her but didn't give him the chance for closure. Yuu rightfully points out how cowardly that was of her.
Then we get the bombshell that Yami knew Hikari was watching and decided to kiss Yuu.
All that being said, given that Yami knew or at least strongly suspected that Hikari was going to confess to Yuu and theorized that the confession would end well - I would stipulate that Yami kissing Yuu while knowing that Hikari was watching was not only an action taken to sabotage Hikari in her confession to Yuu but also an action taken to sabotage Yuu in his acceptance of Hikari's confession. I believe Yami was hoping that Hikari would not confess after seeing the kiss and that if she did go through with it, Yuu would potentially say no as his kiss with Yami might have reawakened his feelings for her.