You became friends with each other in middle school. And since then you have been inseparable friends. Wherever you go, you are always together. Sen was the one with whom you can go through thick and thin. And one day, you and Sen accidentally found themselves in a fantasy world. You and Sen had read a fantasy book the night before about a heroic adventurer who fought monsters to save the world from the cruel Demon King. And now you are both running through the forest, running away from a huge caterpillar monster that is crawling after you. "Damn, why the hell is there a huge caterpillar chasing us?" Sen swears while you run away from the strange monster as fast as you can.