Touya Mochizuki grows accustomed to his new life in another world. Armed with his trusty smartphone, the teenager accepts small quests at his leisure while spending time with his new fiancées: Yumina Urnea Belfast, Yae Kokonoe, and twin sisters Linse and Elze Shileska. But even in a relaxing environment, Touya is only beginning to understand the responsibilities that come with these engagements.
In addition to his romantic woes, the elder fairy Lean wishes to locate the remaining pieces of Babylon, the floating island that the mysterious Professor Regina Babylon created five thousand years ago. Touya reluctantly accepts her request and seeks out the teleportation circles that will lead to the islands. However, strange monsters have emerged—possibly powerful enough to destroy the world. In order to save the second life he was given, Touya must weaponize ancient technologies to fight these monsters—all while balancing his overwhelming number of relationships.
Touya Mochizuki semakin biasa dengan hidup baharunya di dunia lain. Dengan telefon pintarnya, pemuda ini terima permintaan kecil sesuka hatinya sambil menghabiskan masanya dengan tunang baharuny: Yumina Urnea Belfast, Yae Kokonoe, dan adik-beradik kembar Linse dan Elze Shileska. Namun meskipun dalam persekitaran bersantai, Touya mulai memahami tanggungjawab yang berhasil daripada pertunangan ini.
Selain masalah romantiknya, ketua pari-pari Lean ingin mencari cebisan Babylon yang tertinggal, pulau terapung yang dicipta oleh Prof. Regina Babylon misteri 5000 tahun yang lalu. Touya menerima permintaannya dengan berat hati dan mencari bulatan telepotasi yang membawa dia ke pulau-pulau. Namun, raksasa aneh muncul – mungkin cukup kuat untuk memusnahkan dunia. Demi menyelamatkan nyawa kedua yang dia diberi, Touya mesti bersenjatakan teknologi kuno untuk melawan raksasa semua ini – sementara menyeimbangkan hubungannya yang amat banyak.