Okay, so I've been playing Senran Kagura Shinovi Versus. Tonight, I checked out the Estival Versus OAD that came with the next game. And to my surprise... in it was a GTS AND BE scene.
Resident mad scientist Haruka of the Crimson Squad has been working on a drug that makes anything bigger. However it is incomplete. She took it out of her bag and placed it on the ground at the pool where a competition was going on. Later, when all 4 groups are being attacked by some mysterious dark shinobi that appeared out of nowhere, ditz and uber masochist Ryouna of the new Hebijo Girls finds said drug, thinking it is something to drink and downs it. After the steam clears from the fight, she appears as a GTS! And then a few minutes later, as she is getting more aroused as the girls start attacking her to make her sweat out the drug... her breasts grow even bigger in size! (And she's a natural I-cup)
Here is a link to the sub of the OAD set right at the start of the scene.
Senran Kagura Estival Versus OVA (REALLY NSFW!!!)
Enjoy!
-Kai