Magical Explorer, Vol, 11 (light novel)

Years ago, a powerful curse was placed on the genius inventor Anemone that slowly drains her of life, and the day of her demise is fast approaching. To save her from death, Takioto proposes something shocking: travelling to the past to defeat the demon that hexed Anemone. In going back in time, however, Takioto and his team also get caught up in an event from Yuika’s childhood where she is kidnapped as a sacrifice for the very same demon. Naturally, Takioto has a plan to rescue them the two heroines in one fell swoop—but will it really be enough to ensure a bright future for them both?