Grendizer Giga (グレンダイザー ギガ) is a manga reboot of the original Grendizer story by Go Nagai. The manga began its run on the September 19, 2014 in Akita Shoten's Champion RED before ending on July 19, 2015 at eleven issues. It features an alternative to the original story that stands out on its own rather than be connected to previous entries of the Mazinger franchise.
According to an interview with the Hobby Japan magazine, Spaceship; mangaka Go Nagai was scheduled to only produce two volumes worth of content. He also stated that he would like to continue the manga at a later date though under different circumstances. To promote release of the first volume, an animated PV was created by Dynamic Productions and published on YouTube. The inclusion of the character Cutey Honey in the manga was stated to be because of an expansion for including Danbei, given his role in the Cutey Honey franchise as a whole.
UFOs have appeared invading Earth and popular transfer student (especially with his host family's daughter, Hikaru Makiba) Daisuke Uryu is thrown into the conflict piloting a super robot after his 'sister' the assist android Maria restores his memories as the prince Ruke Fleed. Piloting the Grendizer Giga the last piece of the destroyed Planet Fleed, Daisuke fights against its destroyers the Vegan Empire as they invade Earth with their Battle Ogres and Battle Trolls. He is also assisted by another android called Maria 2 who pilots the giant robot Florian Beet to assist Grendizer when Ruke is in danger. Ruke keeps his identity a secret by keeping his memories clean and live incognito as Daisuke. At school Daisuke befriends Yuji Daimon, the son of the director of the Daimon Space Science Laboratory which grants Daisuke access to the labs. As the attacks continue, the Makiba family start to fight back as well revealing their own secrets such as the fact they knew Daisuke's secret all along, Danbei and Nao Jiro being cyborgs, and Hikaru is actually Cutey Honey.
Daisuke eventually lets Yuji and Honey in on his secret as the battles start to get more intense. He requests their help to defeat the vanguard of the invasion. With their assistance, the Grendizer stood a better chance at pushing their forces back and stopping the invasion. Ruke thanks his friends for their help with peace returning to Earth.
During its initial releases, fans of the original Grendizer praised the manga for re-tweaking the formula of the original series as well as the designs of the characters and the battle scenes. However the series was both praised and criticized for showing connections to previous series including the roles of the main characters occupied by the Makiba Family and Space Laboratory as well as the inclusion of Cutey Honey. The series' main criticism was the plot's short pacing and lack of character development.
- Grendizer Giga shows a couple similarities to the multimedia franchise Cobra:
- Daisuke's memories as well as personality change is similar to Cobra's own change in memories and appearance to hide from enemies.
- Maria is an android that assists Ruke in battle much like Cobra's own android partner Lady Armaroid.