-Opening-

We see an army of Demons, Villains, Devils, and Curses slowly walking forward, each of them wearing a dark grin while covered in a mysterious aura. All Might, Gojo, Nanami, Aizawa, Gyomei, Urokodaki, Uzui, and a bunch of other heroes are seen charging at them, as we get a small glimpse of Yajin looking at the screen with red eyes, as the title card comes into view.

Divine Academy

Always you're there with me
When my real story moves on
We will keep on fighting
All the time starting now

Yajin and Akemi are seen sleeping in bed, the two dangling from their beds, before falling to the floor in a comedic fashion. Master Roshi heard the commotion and shook his head, chuckling to himself, as Vomi smiles before looking over a certain picture with a sad look on her face, then quickly hitting Roshi in the head as she sensed him getting close.

Nankai datte ushinatta mono ni tachimukatte
Zenbu keshisatte omoidashita

Izuku is seen heading out the door with his mom waving him goodbye, Tanjiro is seen securing his sword as he takes a deep breath, Issei is seen peeping on girls in a locker room before being found and beat up, Yuji is seen walking with his hands in his pockets, before looking up as the sky becomes dark.

There's nothing to change in me
There's nothing to change in you
What is the correct answer?
Kanarazu

We see a few Demons, Devils, and Curses standing next to each other a mountain, slowly panning over to each of them, as we get a close up of an unknown person that gave a creepy grin, as their body blacked out with their eyes glowing red, as we see Yajin grits his teeth before taking a fighting stance.

Ima kuchihateta sadame no naka de
Tatakai nagara te ni ireta

Akemi rushes in and punches a few demons away, as one came up behind her but what kicked away by Izuku. Two devils flew in towards them, but Issei appeared with a red gauntlet in his left hand and fired a red energy wave at them. Both Tanjiro and Yuji both fly back, the two looking beat up, as all of them stood back to back at the army around them. 

Boku no inochi wo sasageru hi made
This is my only way
Kono mama

Yajin, seeing this, prepared to help, but turned when he felt something behind him and sees the unknown figure behind him. He clenches his fist, his body being covered by an unknown energy, as his eyes turned red, then glares at the unknown figure with rage.

I will stay alive
Praying for myself
I will stay alive
Praying for myself

Yajin fires a single ball of Ki, to which the unknown figure disperses it with a flick of their wrists, as they jumped into the air and attempted an eagle kick, to which Yajin dodged, as the two entered combat, before locking hands. As we see Akemi, Izuku, Issei, Tanjiro, and Yuji all gritting their teeth's, looking beat up, as Yajin gives one last roar, as both his and the unknown figure raises their energy as high as they could. We then get glimpses of the students at Divine Academy, followed by the teachers, Roshi, Vomi, Chronoa, Okara, Ichiro, Yamoshi, and Nathan, then the unknow figure, as we see Yajin standing on a cliff with everyone behind him as the screen turns to black.

-Opening End-

(Shadow2190 here you go man, hope it turned out okay)