What if Kotonoha had arrived at Makoto's apartment a little earlier?

This takes place halfway into the last episode. Makoto and Sekai are in Makoto's apartment. Kotonoha is on her way to Makoto's Apartment. Makoto waits in the living room while Sekai makes tea. The teapot begins to whistle.

'Ba-Ding!' Makoto's cell phone chimes.

"Huh? From Sekai?" Makoto wonders, opening his phone.

Sorry

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Goodbye

Makoto turns around right as Sekai lunges at him, plunging the knife into his abdomen. Makoto jerks backwards and falls to the floor.

Kotonoha opens the front door with a bag of groceries for dinner. Her eyes fly open wide as she observes Sekai standing over Makoto, ready to stab him again.

"NO!" Kotonoha screams and runs at Sekai. She swings the grocery bag and knocks away Sekai's knife. Kotonoha tackles Sekai and ends up on top of her.

"How dare you lay your hands on Makoto?" Kotonoha asks, tears welling her eyes.

To add emphasis to this sentence, she bashes Sekai's head against the floor.

"Kotonoha…" Makoto whispers as he helplessly watches his friends fight.

"How…" Bash.

"Could…" Bash.

"You?" Crunch. Kotonoha's hits are getting harder. Sekai is gasping for breath, her eyes rolling in their sockets.

"My…" Smash. Blood spatters with this hit. Sekai's eyes go different dilations.

"Poor…" Smash. Sekai's body convulses with each hit.

"Makoto…" Smash.

Kotonoha lifts Sekai up to a sitting position by her shoulders. Sekai's head lolls around limply.

"Aargh!" Kotonoha lets out a gutteral, animal-like scream. She takes sekai's face in one hand and smashes her head into the floor with all her might.

Sekai doesn't respond, her unseeing eyes staring at the ceiling.

Kotonoha crawls over to makoto. She lays beside him and gazes into his eyes.

"Kotonoha…" Makoto whispers. She puts a finger across his lips.

"It's OK. I'll take care of everything…" With that she stands up, wiping her face and smearing blood across it. She throws a tablecloth over Sekai and carries Makoto to his bed.

After dressing his wound, she kneels at his side, gazing at his sleeping face. She gently strokes his hair.

"Now we can be together. No interruptions."

She stands and goes to get a saw. "Only one more thing to take care of."