Kinoshita Mahou Koumuten: Isekai Kouhou de Saikyou no Ie Zukuri wo

I'll make my dream home a reality in another world! Kinoshita Takeru, a high school student, is transported to another world through class transfer. While his classmates are recognized as heroes and sages, the job Takeru is given is...--[Construction Company]!? With zero combat ability, he is put in charge of the castle lord of the frontier land of Gaurea! However, Gaurea Fortress has a terrible sanitary environment that would be unthinkable in modern Japan... "I might be able to improve it if I use this power!!" Unable to bear it any longer, Takeru uses the power of his [Construction Company] to renovate the fortress in a modern style!? A production-oriented DIY slow-life other-world fantasy begins, making full use of the special job of [Construction Company]! (Source: SB Creative, translated)