Rehabilitation Training

Rehabilitation Training is a form of recovery training that Tanjiro Kamado, Zenitsu Agatsuma and Inosuke Hashibira were required to take following their battle with the Spider Family. Due to the severe injuries they sustained from this mission, Shinobu Kocho had them undergo the training in order to fully heal their bodies for upcoming missions in the Demon Slayer Corps. Through three unique sessions and extensive, lengthy training under Aoi Kanzaki and Kanao Tsuyuri, the three Demon Slayers were once again in top condition and even became more powerful after learning a new technique.

Training
The training starts with full-body stretches, follows up with reflexes training and ends with a full-body training.

Full-body stretches
The first part of the training methods used in the Rehabilitation Training was stretching. The trainee will lie down on a futon while Sumi Nakahara, Kiyo Terauchi and Naho Takada would try to loosen up the trainee's stiff muscles. The three would stretch them, making emphasis on their arms, torso, legs and joints. This aided with regaining flexibility and makes the bodies limber for training; an important strength that is accentuated by the fact that the trio had spent much time in bed.

The stretching session is shown to be quite rigorous and painful, evident by the usually flexible Inosuke crying visible tears through his boar mask upon being stretched out. The only person who did not feel any pain was Zenitsu, who was seen laughing and in completely bliss as the three girls were in the process of making his body limber, simply because he enjoyed the feeling of being touched by girls.

It is apparent that the stretching is only used to help their bodies warm up for the other two components of the training, as Sumi, Kiyo and Naho are not seen performing the procedure past the initial stages of rehabilitation.

Reflexes test
The second part involve honing their reflexes and improving them. Since their in-bed recovery was slow and lengthy, their reaction speed likely would have decreased considerably. The test was performed by both Aoi and Kanao, with the latter being the main challenger to defeat.

The participants sit facing each other across a table with multiple cups on it. Each of the cups contains medicinal tea that can be applied topically. The objective is picking up a cup and splashing your opponent, while they try do so in return. However, both challengers are allowed to block the opponent's hand on the chosen cup and prevent them from throwing it, leaving the opponent to pick up another before being hit, or block their chosen cup to then make them pick up another.

Since Tanjiro seemed the most willing to improve initially, Kanao was his opponent during most of his training, while Aoi initially served as Zenitsu's and Inosuke's. Soon, the two were able to beat Aoi, leaving Kanao as their new opponent.

Full-Body training
The last part involves what is essentially an enhanced game of tag, with the objective being to grab the opponent attempting to escape.

The opponents once again were Aoi and Kanao, with Kanao again being the final goal to achieve. As with the previous test, Zenitsu and Inosuke were able to beat Aoi rather soundly, which left Kanao as the new opponent.

Total Concentration: Constant
Initially, Kanao was unchallenged by none of the three, owing to both her mastery of Total Concentration: Constant, and her more extensive training and skills as Shinobu Kocho's Tsuguko. Zenitsu and Inosuke became downcast and were unwilling to continue rehabilitation just to be beaten, leaving Tanjiro as the only one to push onwards. Wanting to know how Kanao was so ahead, he was told by Sumi, Kiyo and Naho about her usage of Total Concentration throughout the day, as well as the fact that all the Hashira have mastered it, given them the physical advantage over normal Demon Slayers.

Tanjiro initially attempted to do so but failed, because of the incredibly taxing exhaustion on the body when using it for long periods. Nonetheless, he persevered and used his knowledge of Sakonji Urokodaki's teachings to help him improve lung power. He was then told of a technique involving very hard hollow gourds, with the aim being to break them just by blowing into them. After seeing the large gourd able to be broken by Kanao, Tanjiro became greatly motivated to persist and master it, even enlisting the girls' assistance to help him maintain his breathing while asleep.

Eventually, Tanjiro was able to keep up with Kanao; though she was still undefeated, even she was surprised by the speed he managed to improve at. He is then able to break open a small gourd, and his success was seen by Zenitsu and Inosuke. Wanting to improve as well, they consulted Shinobu, who told them about what he is trying to accomplished. Though confused by his explanation, Shinobu's way of saying the technique is simple and through unique motivations, Zenitsu and Inosuke became driven to master Total Concentration: Constant as well. They adopted the drills and techniques Tanjiro had been using and motivated each other in order to help the other improve, getting stronger as one

After successfully maintaining Total Concentration for an entire day without stopping, Tanjiro became the first to beat Kanao in both the reflexes test and full-body exercise. Seeing his triumph, Zenitsu and Inosuke pushed themselves even harder to reach him. In a reflexes test not long after this, Kanao and Tanjiro are both shown to be neck and neck in terms of speed and reaction time, with both each having tens wins over the other. Eventually, all three became capable of breaking open the largest gourd with their breaths, showing that they have all mastered Total Concentration: Constant.