Karen had felt her heart tear apart when Koyomi had ran off, and was sobbing in the kitchen to a confused Tsukihi,

"Waaaah Nee-chan!!" Karen blubbered,

"Onii-chan wouldn't take me on his bed!"

Tsukihi was a mixture of emotions in considering how to deal with the whole situation. But first she had to calm down Karen.

"There, there, It'll be okay!" Tsukihi consoled the crying Karen.

"I played hard to get like Kanbaru-sensei said!! and I jumped Onii-chan's bones, I let him kiss me, grope me, brush my teeth and even put it in my-"

"WAAAAAAH!" Tsukihi found herself completely repulsed by Karen's claims. "Wha- Wha- WHAT DID YOU DO WITH ONII-CHAN?!?!" Tsukihi could feel herself fainting at the prospect of such horrific incestual relations happening in their home.

"And I wanted him to do it too...but he won't! and...and I..."

Tsukihi takes a deep breath.

"Karen maybe you shouldn't follow this path because-"

"I love him Tsukihi!!" Tsukihi is blown over by the declaration and falls back on the kitchen floor.

"I'm madly head over heels, burning, pining, wanting...for Onii-chan." Karen declares, with her palms on her cheeks and tears welling up in her red face.

an incredulous Tsukihi tries to interject.

"Well I love Nii-chan too but-"

"Onii-chan stokes my fire, he warms me up inside, he makes my knees wobble and my heart skips a beat!!"

Karen slams her fist down on one of Tsukihi's new pots and caves it in with her fist.

"Ahhh~" Tsukihi cowers terribly. "I just bought that."

"I want him to look at me and tell me I'm pretty, I want him to spend time with me, and look at me with kindness. I want to kiss him, hold him...I even lust for him!! I think of him whenever I-"

Tsukihi squeaks and covers her face in shock, Karen falls down on her knees.

"...Why won't you love me Nii-chan? Waaaaaah!!.."

Karen buries her blushing face into her hands and screams furiously. She then stops crying, her grief now replaced with rage.

"Gaaaah!...I'm gonna...I'm gonna go kick his ass!"

Karen resolves and stands up.

"Uwaaa!!" Karen shouts and kicks down the door of the house to a frightened Tsukihi.

Karen then takes a deep breath.

"ONII-CHAAN!! YOU MIGHT THINK THIS RAIN WILL SAVE YOU BY HIDING YOUR SCENT, BUT I'VE BEEN SMELLING YOU FOR YEARS!!" Karen shouts.

"I can find you in rain!! And when I do, I'm going to...to...to kick your face!! yeah!!"

Karen runs out with a jog that would rival some kinda futuristic murderbot from a famous movie.

"Araragi Karen! the Ally of Justice! will smite that inconsiderate brother!" Karen promises as she rushes forward with a great gust of wind that blows away the rain, as she makes her way down the street.