I couldn't find this anywhere on the internet, so I bought it and (very roughly) translated it. I figured here's a good place to post it.
>Why why why!? Why did my chest get smaller!?
>Wawa- Senpai is more upset than usual...!
>Lately, she's always been feeling like that. It seems when she's in the dungeon, she's livelier.
>It's like there's nothing more important than her chest
>......
>But when I'm in the dungeon, it's like that! LIKE THAT--!
>AAA--!!!
>Senpai... That's...! Even though I'm hiding my huge breasts
>I wonder if there's any way I can help
>Her eyes are too pure, so- so radiant!
>That's right, senpai, please listen to me-
>>1944828
>Senpai, you always wanted to have a bigger chest, right!?
>Eh! Ah- yeah-
>Senpai, even though your chest is small, I think you're plenty charming enough!
>If you say "even so," I have a proposal...!
>Y-yeah...! I'm happy you're worried about me, but you're talking a lot today...
>Rather, we'll build a school in the dungeon and live there! In that case, your chest won't get smaller...!
>It's a monster floor!!
>Amazing! So you can have a one-sided conversation without paying attention to me. But anyway, I see...!
>If that's so, then even if you don't have the Holy Grail, your chest could get bigger than Nako's...!
>Eh- This isn't such a good thing~
>You go, Sae-chan!
>Aina-senpai!
>I think that's impossible...
>>1944830
>Well then, let's immediately...
>Depart-!
>Ei-
>oh- Ohhh!
>It's here it's here
>It's a D-cup! This is the natural me...!
>Congratulations, Aina-senpai!
>>1944831
>We've made enough progress through the level, so let's get to construction!
>Yeah!
>Then, let's quickly-
>Kya-
>Are- Are you okay, Sae-chan!?
>...!
>Sae-chan, that chest...!
>Nnn...
>Chest bindings...?
>>1944832
>You're the kind of flat chested girl who can't choose her underwear too, right Sae-chan!
>Effective elastic sports bra
>That's what you're interested in?
>Eh?
>Ahem... Take a closer look?
>Her chest is getting bigger and bigger, right? That's a "Super-breast trap", and the Omega Power is causing her to swell!
>That's- That's true! Her bindings are digging in more and more...! If this keeps up, what will happen?
>They could explode!? ...Maybe
>Whaaat?!
>There is no trap like this in-game.
>If you can suck to save her...!
>The Omega Power will get absorbed into Aina, and get even bigger breasts...!
>Really!?
>Just wait, okay? I'll save you, Sae-chan! (While I'm at it, I'll make my breasts huge!)
>Ha- Aah...
>Senpai...
>>1944833
>This is amazing... What cup size is this?
>I think it's probably around a G-cup?
>So if you have G-cups, you can squeeze them into this shape...!
>Hehehe...hehehe... *slurp*
>Senpa-
>A... Aina?
>This isn't good! This person!!
>Boobs
>Huge boobs
>G-cup
>Some kind of switch got flipped~!!
>Right now, am I about this size?
>I think these might be bigger...
>If that's the case, if I don't take this from Sae-chan
>Her breasts will...!
>>1944835
>Ahhhh-
>Hyaa-
>Senpa-
>Nn~ Nn~~
>Wait-
>That's-
>So forcibly-
>Aina-senpai, wai-...! Wait...!
>If you keep sucking like that...
>My chest is getting bigger and bigger...!
>More more!
>I said, anymore is...
>Really bad...!
>>1944836
>Hm...? Some kind of lukewarm breeze just
>...!
>Aina!!! Behind you behind you!
>...?
>It's a shinigami!
>Awawawawa
>Hieeee
>Nkyaa-
>Aina-chan, welcome back~ You're really exhausted... What happened?
>Are you ok?
>Haha... I had huge breasts, and it turns out living in the dungeon really was impossible...
>Obviously, Aina-chan...
>The end
Here's some other stuff I thought was neat. Don't have translations for them since I haven't done that yet, plus I'm on my phone, but I'll post the gist of it.
They go into the dungeon and pick up a lot of the candles that seem to make them go into an erotic trance but makes them stronger. In game, those candles level up the characters.
>>1944933
They pick up enough items and decide to go back home. Saeri sighs in relief that her chest is back to normal.
>>1944934
Pai the fairy suspects something about Saeri's chest and tries to get Aina to convince Saeri to use a candle with her to confirm her suspicion. Saeri agrees because Aina is the one asking.
>>1944935
They light the candle and Saeri starts feeling its effects.
>>1944936
Aina realizes too late that she is also under the effects of the candle by being in the same room.
>>1944937
Aina asks if she can touch Saeri, and Saeri lets her.
>>1944938
>>1944939
They snap out of their trance and Saeri asks Aina if she saw under her bindings, but Aina doesn't seem to remember anything from before.
Aina and Pai meet to try and increase Aina's bust. They decide to pay Nako a visit to see if she has any secret techniques.
>>1944942
Nako doesn't do anything in particular that would increase her bust. Aina asks if she uses any special creams, but Nako does not.
>>1944944
Nako remembers that she eats lots of sweets and suggests she and Aina eat with her then go running. Aina and Pai refuse.
>>1944946
The two overhear Mirei and Marika's voices through the door. Mirei makes lewd moans through the door and Aina decides to investigate because of yuri delusions.
>>1944949
Turns out the lewd noises were just Mirei getting her feet tickled by fish. Aina asks about ways to increase her bust and Mirei steps up to help.
>>1944953
Mirei starts lecturing Aina about things like lifestyle changes and hormone balances. Aina tunes out quickly.
>>1944955
Aina and Pai gorge on sweets and study for days until they give up. Saeri tries to tell her not to give up and says Aina is beautiful regardless that she's flat chested. Aina hugs Saeri, but too tightly.
>>1944958
Saeri's bindings rip, releasing her big breasts. Aina and Pai are shocked, and Saeri tries to hide them, saying that lately her breasts have been growing bigger. Aina and Pai run away feeling betrayed.
Nako stops the party because something is happening to her.
>>1944967
Nako says it feels like someone is fondling her breasts. Aina and Saeri both say they feel it too, though Aina less so. Pai moves in to explain.
>>1944968
They're getting fondled by the unseen hand of the player, which is equivalent to being fondled by a god, basically.
>>1944969
Nako gets fondled again, and Aina worries that the player hates her. Saeri activates a trap, and tries to console Aina.
>>1944971
Saeri offers her body to Aina, unbinding her huge breasts. The trap that Saeri stepped on earlier was a confusion trap. She asks Aina to trust her, but Aina refuses to trust her while she's confused.
>>1944973
Saeri corners Aina, which activates an unequip trap.
>>1944975
Aina's panties fly off and land on Saeri's head, causing her to faint. Panty-less Aina panics, since now the player will be able to fondle her directly. Nako cries for help from the corner.
>>1944977
Aina asks Nako what's wrong, but Nako has been left a quivering mess due to being fondled to orgasm. Aina despairs that she lost to Nako even without underwear. They then get attacked by a shinigami.
>>1944837
this is more /c/ tier, or /a/