Shin Wolford

Shin Wolford is the main character of Kenja no Mago. After dying of an unknown cause, he reincarnated into an unknown world carrying with him a vague memory of his previous life in his previous world. Shin tends to approach his new world of magic through a lens of his old world of science.

[Spoiler] He later becomes the fiancé of Sicily. [/Spoiler]

(Source: Kenja no Mago Wiki)