Miboujin Elf no Kanamori-san

When a boy consoles Kanamori-san, a beautiful elf whose husband has passed away, by saying "I'll marry you myself," she takes him in as her fiancée...? A sweet and precious pure love comedy between a clumsy delinquent boy and the slightly naive Kanamori-san, with an age gap 500 years apart.

(Source: Monthly Action, translated)

Note: Originally a one-shot published in Monthly KiSSCA 2020 Oct. issue, with a sequel in December. It was picked up for full serialization in Comic Action starting 2023-02-25.