Hearing Ren request, the first thing Tsunade did was to check Ren's information and mission history, and she noticed that he was only able to use kenjutsu and that all the mission he did with his team were a bunch of D and C ranks and one A rank where his team went as reinforcement for Naruto's one, and that he did take part in the chunin exam and even reached the finals but did not fight as Orochimaru's attack happened.
Then Tsunade asked "You got a good record on you why do you want to retire?" and Ren answer "Well, Hokage-sama to be more precise it is a temporary retirement, as I feel that I can't improve as much here in the village doing missions, so I want to go to the Land of Iron for the next 3 years to train my kenjutsu and then come back to the village."
Tsunade looked at him and once again at his information then said signing some documents "Very well, I approve, from now on Haruno Ren is relieved from duty and is once again a civilians, and has the permission to leave the village, but if you do not come back 3 year from now you will be declared a missing-nin am I clear?" then she gave him another document with the permit.
Then Ren took off his protector and give it to Tsunade while saying "Thank you Hokage-sama, farewell" then he got out of the Hokage office, and went back home.
Once there he had dinner with his family where he told them of his temporary retirement and his plan to go to the Land of Iron to improve, while at first they were upset about it, in the end they understood Ren's motive about his decision and supported him, while Sakura was more upset about the fact that they won't see each other for a long time, but Ren told her that he will write her every week to calm her down.
The next day he went to tell the news to his teammates and his sensei, once again telling them that he felt that he wasn't improving fast enough and that was why he choose to make this journey then he gave a toy katana and a book named "101 thing to know about begin a parent" to Hayate-sensei while also saying to be careful of the curse.
Then next he went to the Kurama mansion where he had lunch with Yakumo and her parent and then he also told them the news, then after the lunch he spent some time with Yakumo.
They went to the park where they walked around , until they reached the place of their first meeting, so they sat there and started chatting about different topic that went from, the type of illusion to their favorite dish, they spent time like that together till late evening then Ren once again sent Yakumo back home.
Once they reached the front gate Ren give her a Jigokucho scrolls and said "With this you can contact me anywhere, and if you have problems you can alway call me; I will come as fast as possible"
Then Yakumo took the scrolls, looked at Ren and said "Hmm, be safe and come back stronger than ever" then she gave him a kiss on the cheek and blushing rushed inside her home, while Ren stood there stunned for a few minutes, then with a huge grin went back home to prepare for tomorrow's journey.
Once inside his room the first thing Ren did was to send a message to Dosu to meet with him near the Land of Water border, where he will explain his plans, then he made sure to take the scrolls with his Shinigami attire with him , the tent to sleep outside and something to cook with, then he went to sleep.
The next day Ren saidgoodbyes to his family and then went in the direction of the Tatsumi Gate, once there he gave his Hokage signed permit and got out of the village and started his journey toward the border of the Land of Water were he will met with Dosu Kinuta.
The first 3 days were somewhat calm, but the more he got away from the village the more bandits he encounter, and now in the middle of the day surrounded by dozen of bandits corpse Ren thought 'This is another effect of Pedo-sennin attack, the now weakened Konoha doesn't have enough resource to cull all the bandits in the far away regions of the Land of Fire'
Then Ren looked at the sky a decided to find a place to have lunch so after gathering all the corpse in one place he set it on fire with a Hadō #31. Shakkahō (Red Fire Cannon) where he generates and fires an orb of crimson red energy on his palm setting all of them on fire.
After all the bandits corpse were incinerated Ren searched for a source of water, and soon found a small river and a clearing big enough to camp there.
As he prepared the fire to cook the fish he just caught, Ren heard a bear roar and soon after the screech of an unknown animal, curious Ren went to check , and soon he found another of those Arzuros-like bear that was about to kill a small platypus-like animal, it has a turtle-like shell on their back and on his head, shell, front arms and tail has algae-like fur while the rest of his fur is a soft green, it almost seem like a Kappa and it had a big claw injuries on his belly.
On instinct Ren took an Iai stance and then draw and swing Senbonzakura so fast that it seems like he didn't even move, then he said as he took a relaxed stance "Hitotsume: Nadegiri(The First: Killing Stroke)", while the bear is as still as a statue.
As Ren started walking toward the platypus-like animal, the two half of the bear body fall on the ground with a loud thud, as Ren is near the small platypus he notice that the animal is still wary of him but he slowly sat near him and start using Kaido on it.
After Ren finished healing it, he took in his arms and took it back to the camp, and divided hi lunch with it, then he said "Okay little guy, I saved ,healed and fed you ,now you can go back home, be careful of predator" the got up and went in his tent to sleep under the gaze of the orange eye and horizontal pupil of the platypus.
As Ren was preparing hi bedding he felt something enter his tent and when he looked he notice that it was the platypus and asked in a joking tone "What is it you want to follow me now?" and surprisingly the platypus nodded, seeing that Ren though about it then said "You know what? Okay from now on you are my friend, now for a name...Got it! Your name will be Peri!"