Ryutarou Sakagami/Relationships

Suzu Taniguchi
Ryutarou's first girlfriend. The two of them become a couple one year after they and the other students return to Japan. She wishes to go with him to Tortus and spend their days together helping Kouki and the people.

Kouki Amanogawa
Ryutarou's best friend. He tends to support Kouki in his decisions blindly without considering the consequences. Though after Kouki lost his way, Ryutarou decided to take up the task to bring his friend back and give him a good pounding to bring him back to his senses.

Kaori Shirasaki & Shizuku Yaegashi
They are his childhood friends and fellow Returnees group members. Ryutarou only considered them as a friends (unlike Kouki.) Ryutarou allowed them to be in love with Hajime after his survival and obtain monstrous strength to not get on to Hajime's bad side after he murdered Hiyama.

Hajime Nagumo
Ryutarou originally thinks little of Hajime because of his lazy attitude and weak spirit, which goes against his own straight to the point and hardworking nature. He even goes on to tell Kaori that she is wasting time on someone who is a failure. Even after his class is summoned to Tortus, this fact doesn't change for him. And similar to Kouki, he also easily accepted Hajime's supposed death after his fall into the Abyss. In Volume 4, after being rescued by Hajime from the attack of the Demon Cattleya and her army of Monsters and seeing that Hajime has changed in become ruthless against his enemies, Ryutarou became afraid of Hajime that he was willing to kill anyone including his classmates who dares to cross him or harm his friends. Like most of his classmates, he takes Hajime's warning seriously to ensure for his own safety and not get involved with Hajime's bad side after he murdered Hiyama as he doesn't condemned Hajime for it, as Ryutarou will never forgive Hiyama for what he had done.

After Hajime revived Kaori, Ryutarou expressed his gratitude to Hajime as respect for him and his strength.

In Volume 6, after the Demon Invasion and learning the truth about Ehit following both Eri's betrayal and Hiyama's death, Ryutarou, Suzu, Kouki and Shizuku managed to convinced Hajime to give them a second chance to clear the remaining Labyrinths and destroy Ehit.

In Volume 9, when Hajime began to enhanced his classmates armors and weapons, Ryutarou had his gauntlets to be enhanced by Hajime and his gratitude and respect for Hajime had suddenly increased even more when he witnessed of testing his gauntlets newly enhancements. He shown surprised of Hajime's creations are similar to the military armys' weapons and technologies which Ryutarou admires military soldiers and he is highly amazed of Hajime firearms and military vehicles. He starts to feel a kinship towards Hajime because he considers Hajime as a pupil of "Gunnery Sgt. Hartman" just like himself, because of the way how Hajime had trained the Haulia Tribe and the Fleur Knights and begged Hajime to train him as he called him a friend which Hajime got touched by and accept him to train.

While Hajime became more popular to beautiful girls than Kouki, Ryutarou doesn't has any jealously on Hajime. Unlike Kouki, Ryutarou valued his friends instead of pride and as he letting Kaori and Shizuku to be in love with Hajime.

When Hajime and Yue were creating the Crystal Key to bring them back to Japan, Ryutarou and the others experienced what Hajime went through when he fell in the Great Orcus Labyrinth. Witnessing the pain, suffering and loneliness Hajime went through and his determination to return home, Ryutarou felt extremely sympathy for Hajime. He also gives more respect for Hajime's willpower, understanding that neither he or the others could have overcome the harsh Abyss like Hajime did, and realize how easy they had it compared to him.

After returning to Japan, Ryutarou appreciated Hajime for all he done for him and the other classmates. As a token of gratitude, Ryutarou and his classmates gave him a nickname as the "God Slaying Demon King".

Yue
Ryutarou is infatuated with Yue at first sight when she arrives to protect him and the other students in the Great Orcus Labyrinth, but doesn't try to make any advances on her nor does he speak about it to others, because he knows that she loves Hajime and would reject him, and he doesn't want to get on Hajime's bad side. Yue seems to appreciate Ryutarou for his kind words unlike Kouki who Yue finds annoying.

Ehit (Deceased)
Ryutarou once respected so-called "God" Ehit after he was summoned and blessed as one of his so-called "Heroes". However, learning from Aiko and Princess Liliana of Ehit's true nature, Ryutarou turned against Ehit and sided with Hajime.

Daisuke Hiyama (Deceased)
Ryutarou hated Daisuke as he saw him as a creep and jerk after his cruelty to Hajime. From Hajime's presumably death, Ryutarou was easily manipulated by Daisuke's lies. When Daisuke betrayed his classmates and temporarily killed Kaori, Ryutarou's dislike towards Daisuke increased even more. Though Ryutarou was fearful when Hajime brutality murdered Daisuke, Ryutarou doesn't condemned Hajime for murdering Hiyama. When learned that Hajime's "fall" wasn't an accident, Ryutarou abandoned what's left of his sympathy and always remembers Daisuke Hiyama as selfish, deluded traitor.

Soul Sisters
Despite being Kouki's best friend, the Soul Sisters mistreated and tormented Ryutarou as one of the people which are Soul Sisters sworn enemies (the other being Hajime).

Eri Nakamura (Deceased)
Eri was one of Ryutarou's close friends. However, in truth, she manipulated him and their classmates and betrayed their party when she sided with the Demons. She has planned an assassination plot to kill Ryutarou and the rest of her classmates due to him and the others stood in her way to make Kouki hers. Upon their reunion, Ryutarou shown in hostility towards Eri when she ignored Suzu and later himself due to her focusing on Kouki.