After Yuzu and Karin birth, Ichigo was introduced to Ryuken who he found out was actually his uncle.
Ryuken told ichigo that he had a son the same age as Ichigo who was training with his father who was ichigo grandpa. Ichigo wanting to save him as he think that the Quincy died for no reason at all. So Ichigo told him that he wanted to meet him and want him to train ichigo.
Ryuken was surprised with Ichigo statement and just asked him why he wants to train. Ichigo just said that just like his name he will protect or be a guardian for his loves one. Ryuken smiled seeing this something that does not often happen since his wife died.( I'm not sure when she died or how she died)
The next day ichigo met up with Uryu and Soken Ishida who was his grandfather. Uryu seeing his cousin that he didn't he had until now was quite happy since he has someone around his age training with him and could become someone who would be able to push each other further.
Soken seeing ichigo smiled before introducing himself and Uryu. He then started training both of them and was astonished by Ichigo's talent.
Uryu was also surprised seeing ichigo being so talented. Soken seeing Ichigo taking everything he taught like a sponge easily was worried as he could see Uryu feeling jealous and neglected.
Ichigo noticing this told Uryu some motivation and said that he would one day be able to catch up to each other and that both of them would be rivals that help each other or improve and protect each other.
Uryu smiled hearing this and was more confident and both of them started training under Soken. Ryuken saw this from a distance and smiled. He hoped that his father and Ichigo could give Uryu the happiness he couldn't.
In a few days, Soken was with Ichigo talking with each other when all of a sudden a bunch of hollow appeared.
Soken tried his best to kill all the hollows while telling ichigo to run. Ichigo knowing that this was some shinigami wanted Soken dead stayed and helped kill all the hollows. Soon four to five shinigamis appeared in front of them and frown seeing them alive. They expressed their anger and started attacking Soken.
Soken hoping that his death would allow quincys and shinigamis to be at peace and Ichigo being safe didn't defend himself. Ichigo seeing Soken not defending himself was angry since they took Soken kindness and peace loving nature to their advantage. He called out his zanpakutou before killing all the shinigami in a blink of an eye.
Soken was wide eyed seeing this and told ichigo why he did it. Ichigo replied with saying that those shinigami was taking advantage of him and that they won't stop anything.
Soken hearing this is sad as his dream of them being able to live peacefully get further and further. Ichigo seeing this told his grandfather to not worry since he will be the one to accomplish this dream since he has both shinigami and Quincy blood in him.
It was his responsibility to become the bridge to their races friendship. Soken just smiled before going home with Ichigo.