It was serialized in Shogakukan's seinen manga magazine Big Comic Superior from December 2017 to September 2021, with its chapters collected in ten tankōbon volumes.

Chiho discovers that the device lets her grow into a giant with incredible strength and durability, and shrink back to her regular size, though the growth only applies to her body, tearing her clothing and leaving her naked.

These include a rain of excrement; a famous actor running naked through Shinjuku; the death of a celebrity rumored to be a murderer; and an earthquake.

After it becomes known that Chiho, now a celebrity, is dating a highschool student, she loses entertainment industry opportunities and they decide to put their relationship on hold.

A group of time travelers from 2135, dressed like the old man and with similar growth powers, find Chiho, and tell her that two artificial intelligences, Socrates and Plato, were created in 2019 and leaked onto the internet, and, connecting to a Chinese satellite, built a gigantic facility in space from debris; using its machinery, including a bio-printer, the AIs operated Enjoy the End to understand humanity.

Gigant, written and illustrated by Hiroya Oku, was serialized in Shogakukan's seinen manga magazine Big Comic Superior from December 8, 2017.