"BUG" is a so-called "Isekai" fantasy comic.
One day, a girl suddenly flies to “Isekai” and interacts with people in the world. However, the girl can go back and forth between “Isekai” and the world where she originally lived, so the situation is a bit different from the usual “Isekai” fantasy.

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In addition, they are introduced not from the girl's own perspective, but from the perspective of another parent and child. It's an unusual web comic.