After fighting through numerous traps and laser-trip alarms by working around the Monokumas and the dead Towa Group personnel, the four of them made it to the bottom level where the trump card was hidden.

As it turned out, this trump card was actually a giant robot named Big Bang Monokuma, the secret weapon built by Towa Group to defend the city. Byakuya freaked out, asking why Towa Group were producing Monokumas in their secret factory. Oyano (jataro's older sister) explained that the Monokumas they made were initially introduced as helper robots, with plans on other functionalities to be installed on them. This explained the large variety of Monokumas the girls have encountered.

During their conversation, kotoko's robot abruptly broke in in an attempt to destroy the Big Bang Monokuma (which didn't work obviously)

byakuya (ultimate writing prodigy ✍️): "wh-what is this?!"

makoto (ultimate nothing): "that kid.. she's the one who wanted to let us go, right?"

kotoko (ultimate social studies 📖): "...found you... demons... i can't believe it... hiding something like this.."

oyano (ultimate older sister): "let me guess did he (jataro) told you this? If he can't control it, he wants you to destroy it? Well, I won't let t happen! This is the hope we've finally got for ourselves..."

kotoko (ultimate social studies 📖) (beginning to break down and tear up): "you want to crush our paradise...with something like this... I won't let you.. everyone expects so much of the Warriors of hope... and of me... to meet these expectations, I have to build paradise all by myself!! So expect more of me!! I'll work harder! I'll do it, anything, just please don't abandon me... father... mother...! Big bro leon! Jataro!! More, more, more! Expect more from me!!"

oyano (ultimate older sister): "w-what's wrong with her!? She's completely batshit crazy!!"

makoto (ultimate nothing): "how did she get like this...?"