My Grandpa's Stories Can't Be This Weird!

Though is title logo resembles a certain light novel, and his younger sister is particularly cute, the student council president doesn't have any mystery to solve about it.
It is just as it says, a comic about a grandpa telling his grandson a strange story.
What is strange about it and why is something you'll have to read the comic to find out!
You'll find yourself chuckling while you read, as you enjoy the charming world of this grandpa.