Suddenly, “Babel” appeared in the capital. A tower where one can strike it rich, filled with treasures and rare materials. But inside awaits deadly traps and ferocious monsters that mock those who enter. Many adventurers challenge “Babel” in hopes of conquering it. Kyoichiro is one such adventurer. But this is not his first attempt. Through countless regressions, he has experienced challenge after challenge, and death after death. All of it—for the sake of saving his beloved childhood friend and comrades. "I will save them, no matter what. This time for sure." With the fastest clear—the mission is to rescue his childhood friend! The 99th challenge begins—!