Spoilers through the end of LN 14. Having read through arc IV is recommended; if you are anime only waiting for the second half of the second season is advised. Satella's personality gains a moment of dominance over the Witch of Envy, and as a result an 11 year old Subaru is summoned in the Ellior Forest with a similarly young Emilia.

Full Title: That Time I Got Blasted Back to My Original World Along with the Half-Elf Girl I'm In Love With In the aftermath of conquering the Pleiades Watchtower the cost of using Cor Leonis is much more severe on Subaru. Worried Emilia stays by his side and delays showing off Volcanica's state. A series of events sees Subaru and Emilia sent to Earth instead of Vollachia.