Rentaro Satomi Becomes a Tendo

Rentaro Satomi Becomes a Tendo‏‎ is an event that took place ten years prior to the current storyline.

Prologue
Rentaro Satomi is born to Takaharu and Mafuyu in the year 2015, six years prior to the sudden appearance of the Gastrea Virus. The young boy lives with his father and mother until the age of six, separated from the two as a result of their death. During their funeral, Rentaro is accompanied by Kikunojyo Tendo and several other characters his parents were familiar with. Among the suffering, Rentaro can only stare at what remains of their lives: a burned charcoal, when Kikunojyo speaks to him about their presence—which he claims will be greatly missed. Momentarily, he is asked by the latter if he wold like to live with him, as a Tendo.

New Family
Without a second to waste, Rentaro denies the man's offer, quickly picking himself up and running away from their current whereabouts. As he runs down the streets, he reminds himself that his parents are still alive, just ragging for salvation; something which he makes his goal.

However, during that same year, Rentaro enters the Tendo household as Kikunojyo's adopted son, meeting Kisara Tendo and becoming great friends with the young girl. Kisara notes Rentaro's goal, claiming that he continues to utter the same words heaps of times. When living in the Tendo household, Rentaro was bullied continuously by Kisara's many brothers. Around the time the Gastrea War commenced, Rentaro saved Kisara from an attacking Gastrea. In return however, his left limbs and left eye were taken in the sudden invasion. He is later given a chance at life when a doctor replaces those limbs with Varanium.

Aftermath
In the following years, Rentaro and Kisara leave the Tendo house to live on their own, eventually creating their own Civil Security Corporation, titled Tendo Civil Security. Howbeit, Kisara leaves on bad terms with her grandfather Kikunojyo; making him the sworn target of her revenge.

After leaving the Tendo house, Rentaro becomes a Promoter in the year 2030, meeting Enju Aihara, an Initiator, shortly afterwards.