When I returned from exploring the dungeon to save the world, I found out that my lover had been stolen, and I was blamed for the failed expedition. Enraged, I quit Japan’s strongest party—only for them to self-destruct on their own.

“The only one who was kind to me was my ex-girlfriend’s super cute younger sister.

My name is Koichi Okita, and I was a frontline fighter in Japan’s strongest party, tasked with conquering the Tokyo Dungeon—one of the seven high-level dungeons that must be cleared to prevent the world’s destruction.

The road to dungeon conquest was harsh, grueling, and long. After six months of relentless exploration, I returned, carrying my wounded comrades, only to be met with betrayal—my girlfriend had been stolen by the party leader, who had stayed behind due to an injury. On top of that, I was unjustly blamed for the expedition’s failure.

Once the strongest explorer and a highly popular dungeon-streamer, my reputation crumbled overnight. Amid public backlash and relentless criticism, I left the party.

I didn’t care anymore. They could do whatever they wanted.

That’s what I thought—until only one person stood by me: Haruka Miyanaga, my ex-girlfriend’s younger sister and a fellow party member, who comforted me in my lowest moments.

After leaving the party, I realized something—aside from Haruka, the rest of them were trash. And so, with a newfound sense of relief, I moved forward…”