The half-sibling of Tetsuhiko Kai. She introduces herself as the "Jack of All Trades".

She smiles just for me. Her name is Kachi Shirokusa and she's even an award-winning high school girl writer! And she's beautiful! I know that she's totally out of reach for me, a normal high school kid named Maru Sueharu! But I think something's there... No, there's definitely something there! Or so I thought... but Kachi has a boyfriend?! Seeing me depressed, my friend ever since we were little who's cute, cheerful, and loves to look after others, Shida Kuroha... who also apparently had no problem telling me that she likes me for some reason just suggested, "Let's get revenge." 
 
(Source: Crunchyroll)

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My childhood friend Shida Kuroha seems to have feelings for me. She lives next door, and is small and cute. With an outgoing character, she’s the caring Onee-san type, this being one of her greatest strengths. 

…But, I already have my first love, the beautiful idol of our school, and the award-winning author high school girl, Kachi Shirokusa! Thinking about it rationally, I should have no chances with her, but, while walking home from school, she only talks to me, with a smile even! I might actually have a chance, don’t you think?! 

Or so I thought, but then I heard that Shirokusa already has a boyfriend, and my life took a turn for the worse. I want to die. Why is it not me?! Even though she was my first love…As I was drowning in despair and depression, Kuroha whispered.
 
—If it’s that tough for you, then how about we get revenge? The best revenge ever, that is~

My childhood friend Shida Kuroha seems to have feelings for me. She lives next door, and is small and cute. With an outgoing character, she’s the caring Onee-san type, this being one of her greatest strengths.
 
…But, I already have my first love, the beautiful idol of our school, and the award-winning author high school girl, Kachi Shirokusa! Thinking about it rationally, I should have no chances with her, but, while walking home from school, she only talks to me, with a smile even! I might actually have a chance, don’t you think?!
 
Or so I thought, but then I heard that Shirokusa already has a boyfriend, and my life took a turn for the worse. I want to die. Why is it not me?! Even though she was my first love…As I was drowning in despair and depression, Kuroha whispered.
 
—If it’s that tough for you, then how about we get revenge? The best revenge ever, that is~

Rena Asagi