A portal tears open in the middle of Ginza, Tokyo. Medieval soldiers pour through, slaughtering civilians, abducting hundreds, and vanishing back through the Gate before Japan can respond. The Japanese government calls it an act of aggression by an unknown foreign power. The Diet authorizes a full-scale military response. The JSDF mobilizes.

Now, on Day 1, Japan sends its retribution force through the Gate. On the other side: the Special Region — a world of empires, vassal kingdoms, demi-humans, dragons, magic, and gods. The Empire that launched the Ginza attack is massing a coalition army to crush the invaders. They have no idea what's coming.

You can play as any canon character — Yōji, Pina, Rory, Zorzal, anyone. Self-insert as a JSDF soldier, an Imperial senator, a demi-human refugee, a mercenary, a mage. Build an alternate universe. Create your own character from scratch. The Gate is open. The collision begins now.

Two civilizations. Zero shared knowledge. Absolute military realism. Full butterfly divergence — your choices reshape the canon timeline. The Empire's army is a day or two out. What do you do?