Relationships
Taiju
Taiju and Senku have been friends since childhood. In the past, Senku was protected by Taiju from bullies. This led Senku to develop a deep sense of respect and trust towards Taiju even though he is an airhead. When Senku was depetrified, he did everything he could to survive but admitted he needed Taiju and his endurance to overcome the obstables to come. He later, become one of the main units, especially power and excavation team to farm wheat and opening Mine Deposit.
Yuzuriha
Yuzuriha and Senku are friends through Taiju, Senku knows how deeply Taiju loves Yuzuriha and respects his friends love interest. He is even willing to sacrifice himself to protect her and abandons the depetrification formula to Tsusaka. She possess a genuine ability of tailoring which was useful for the Kingdom of Science.
Tsukasa
Since his depetrification, Senku was always wary of Tsukasa and his goals. Because he was too strong, Senku had no other choice but to consider the possibility of Tsukasa and him not sharing the same principals. Tsukasa however deeply respects Senku and asks him to abandon science so that he doesn't have to kill him. Tsukasa then shares his regrets of not having talked to Senku 3700 years ago, saying that he may have became his very first friend, to which Senku replies ''probably''.
Kohaku
Kohaku sees Senku as a gentleman and she is rather impressed by him. She first saw him sacrificing himself to save Yuzuriha and since that moment, she admitted that she was very interested in him. She led him to the Ishigami Village where Senku met all the other villagers. She did not trust in Senku at first but along the adventures, she accepts him and trusts him with very important things, like Ruri's life. Also, she may consider him a very close friend as she was not much offended on how Senku call her a Lioness.
Chrome
At first, Senku and Chrome had a rivalry. Chrome proclaimed to be a genius sorcerer and Senku claimed to be a scientist. Chrome showed off his skill to impress Senku, Koharu, Kinrou and Ginrou but was completely overwhelmed when Senku revealed that he knew all of his tricks. Nonetheless, Senku was impressed by all the knowledge that Chrome had learned all by himself. In a way, he reminded him of himself. After a small dual between the two, Chrome loses to Senku and joins his kingdom of science. They then team up to overcome the challenges towards creating the cure-all for Ruri. Chrome eventually assist Senku in many ways, including discovering the Ore Deposit that the Kingdom of Science needed for their campaign.
Homura
Senku uses the blue jewel powder to track her. chapter 62
Asagiri Gen
A twisted mentalist. Originally sent by Tsukasa as a spy, later defected to work with Senku. Realizing that he can revive the science, he become one of the most trusted retainers to manipulate and even to do Senku's bidding.
Nanami Ryusui
The child of the owner of Nanami Conglomerate. Despite his twisted personality, Senku and Gen's tag team are even able to twist more situation, much to his shock. Together, they team up to search Sagara Oil Fields that has been discovered by Kohaku and preparing for a journey in a search of the source of petrification.
Ukyo
Former SDF Navy that serves as a submarine operator. He becomes one of the vital assets for Science of Kingdom due to his perk of superhuman hearing.