Substitute Girlfriend ~I'll Become a Slutty Gal to Protect My Best Friend!~ ^Final

"Wait, Sui-chan... You got a boyfriend!?"

I received a shocking confession from my best friend, Sumi Mizuki, that she had gotten a boyfriend.
And to top it off, her partner was none other than the popular and handsome Matsui Tatsumi at our school.
At first, I was celebrating Sui-chan's relationship, as she was my only friend at school.
However, I gradually began to sense that her appearance and behavior were changing for the worse.
SpoilerIn the midst of this, I learned that Tatsumi was setting a trap for Sui-chan, intending to turn her into a slutty gal.
To protect my precious best friend, I confronted Tatsumi and demanded that he break up with her.

"I-I'll be blunt. Please... break up with Sui-chan..."
"Huh? Because you're feeling lonely after losing your best friend, you want her back, huh? Lol"

And the condition Tatsumi presented was to offer my body as a 'substitute' for my friend.

Driven by Tatsumi's love for slutty gals, I was coerced into numerous perverted acts,
transformed into a slutty 'substitute' both in appearance and in spirit.
Before long, I found myself sinking deeper and deeper into this abyss, becoming nothing more than a 'substitute' in every sense.
(TRANSLATED FROM DLsite)

Game is avaialble for Windows , Android (With kirikirdroid2)