Dr. Slump

Dr. Slump is a manga written and illustrated by Akira Toriyama.

Synopsis
Dr. Slump creates a little android girl, Arale, who is very stong, happy, and totally common senseless. They live in Penguin Village where the strangest things happen (e.g., the dawn is announced by a little pig wearing a basquee).
 * Source: https://myanimelist.net/anime/2222/Dr_Slump__Arale-chan

Featured relative giantess: Arale

 * 1) She is the protagonist of this series.
 * 2) She (relatively often) becomes giantess or para-giantess.