 If you liked
Ousama-tachi no Viking
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 ...then you might like
Kimi to Uchuu wo Aruku Tame ni
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Both series feature a main character who is really knowledgeable/smart but has trouble with everyday life and communicating with other people. Ousama is about cyber security and surviving in the business world, while Kimi to Uchuu is about astronomy and more high-school related.
While themes are different they share other similarities as well, like the second main character helping the main character and vice versa (so there is a nice symbiosis between the MCs and it's nice to read).