Rimuru Tempest's Little Sibling

"Impulsivity, Level Max, has been activated."

{???}

"Quest, write a letter and send it to a random person. Reward, a penpal. Failure will result in... BOREDOM!!! Dun, dun, duuuuuuuun!"

{*sigh*}

Rimuru Tempest had made many friends and family during his time in Tensura.
However, what if he wasn't the only one who got reincarnated there?
What if he had a little sister who also got reincarnated in Tensura after she died?
Meet Sachiko Mikami, the younger sister of Satoru Mikami.

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Synopsis - 3/3/25
Ch1 - 3/3/25