Series: Hero Maricha (yuppai)

https://www.pixiv.net/en/artworks/82242184
Original title: ゆうしゃっまりちゃ

An extremely delusional, ungrateful, spoiled, shitheaded, and very stupid pet Maricha disobeys her owner and goes on a "hero quest". Reality and karma hits like a brick almost immediately.
One of the best fitting consequences stories, dumbass threw away a luxurious pet life and both directly and indirectly causes every misfortune she receives.