WARNING: The following contains spoilers for To Your Eternity Episode 9, “Deep Memories,” now streaming on Crunchyroll.
In To Your Eternity, Gugu has a rather complicated relationship with Rean. She's the one who gave him hope for a better life with her ring. However, she also inadvertently turned Gugu into a "monster." Because of his unbearable crush on her, Gugu often finds himself lost for words whenever he talks to Rean -- even more so when he realizes they are very different due to their class and because of how Gugu looks now. But with Rean's encouragement, the two of them begin to bond.
After Fushi rescues Gugu, they start to grow closer. Embracing his "monster" appearance, Gugu has the time of his life, frightening people with his face and Fushi's shapeshifting (usually in the form of Oniguma). But at the mention of returning to the Booze Man's place, Gugu immediately sobers up and is clearly still angry that there's a new organ in his body.
Being on the run without any money takes its toll, and Gugu is too weak from starvation to move anymore. Worried sick, Fushi digs deep into his memories to try to find something to help -- and remembers all the food he's eaten. Fushi concentrates and a pear, the first thing he ate after he took on a human form, suddenly materializes out of his hand. More and more food keeps popping up as Gugu crows with glee.
As Gugu starts getting to know how Fushi's powers work and the extent of his own existence, he takes on a more patient air when talking to him. He explains that the "emptiness" that Fushi felt from the Nameless Boy early in To Your Eternity was known as death. Gugu realizes the "stimulation" that triggers Fushi's abilities is often through physical pain, and most recently through emotional pain. Although he doesn't outright admit it, he considers Fushi his family by giving him permission to "become" him when Gugu dies. Even if he's forgotten by everyone else, at least Gugu will be remembered by Fushi.
Their quiet peace is soon disrupted when Rean appears, having tracked the two of them down thanks to her dog. Without his mask, Gugu feels like he threw away his only chance of living like a human being. Surely monsters can't live with other humans like Rean, Pioran, and Booze Man. Rean pleads with him to return home, saying Booze Man has promised to take the organ out of Gugu's body for free. Even with that tempting offer, Gugu doesn't want to go back.
Rean tells Gugu of how, on the outside, she looks like a pampered and well-loved little girl in a wealthy family. In reality, she's a prisoner -- everything is decided for her and none of what she likes is ever taken into consideration. She has neither freedom nor autonomy.
Their distance is symbolized by the tree that sits between them as they talk. She gives him a pot with holes for eyes to use as a temporary mask, telling him he is still Gugu, regardless of whether he's human or not. As Rean talks, she walks out into the daylight, giving him the choice to metaphorically take her hand and go out into the human world with her. He does indeed, finally leaving from his hiding spot behind the tree to stand beside her. Rean wholly accepts Gugu for who he is, even if he's never comfortable taking off his mask.
As is usually the case in To Your Eternity, Fushi's contentment doesn't last very long. The Creator appears before him and warns that because he didn't receive any stimulation -- meaning he didn't learn or gain anything useful since the last time he fought -- Fushi's going to find himself in an even more disadvantageous situation than the first time.
But the Creator's warning comes true. When Fushi turns into March to distract Rean's maid from taking her back home, he gets dragged up by the tree-like creature and isn't able to fend it off before he gets injured. Gugu runs to his rescue but with Fushi in danger once again, and the enemy seemingly more powerful than before, can the two monster brothers defend against this far more sinister adversary?
