Reset

The reset is a feature built into the fabric of Kumon-mi meant to help maintain the system and give Sensei an opportunity to maximize the happiness he can extract from the world. It appears to be a function of the Wire God, although the Concerned God may have a hand in its activation along with Maya.

How it works
Approximately every three months, all of the people appear to be erased from the world except for Sensei and Maya. At least in the current era of Kumon-mi with a weakened Wire God, it appears that both Sensei and Maya can have some difficulty properly orienting themselves towards the goal of reaching the roof of the school in order to perform the reset.

The reset itself appears to involve Maya praying to the Concerned God for the reset to begin, along with other parameters such as changes in the weather. Maya implies that she can reset on her own if she chooses, but she can also choose to wait for Sensei to arrive. If Sensei and Maya are in physical contact when the reset begins, Sensei will have his mind, memories and progress with the girls brought back in time three months, allowing him to continue his quest for affection and happiness without concern for time moving on. If Maya resets alone, then Sensei's mind is wiped and he is replaced by another with a randomly chosen personality.

Purpose
The purpose of the reset, other than its straightforward purpose of preventing time from progressing and Sensei losing access to his class, is to give Maya an opportunity to test and judge each iteration of Sensei.

The goal of this world is to create a system where Sensei can find happiness and escape from the misery of life. However, as the first iteration of Kumon-mi showed, misery will always find its way in. Sensei Prime had failed to combat the guilt and pain of his own mistakes in life, and as a result had become a shell of his former self. He wanted to create a person who could overcome his own shortcomings and live the life that he himself never could. Not knowing the key ingredients that would create the right personality for such a person, he left it up to a roll of the dice.

Every reset, a randomly generated Sensei is created and is introduced to his new world. For the next three months he gets to know those around him and become familiar with his new life, being observed by Maya the entire while. At the end of each loop, Maya is given a choice: wait for Sensei to arrive on the roof in order to allow him to continue his journey with his current personality, or reset without him and reroll for a better Sensei. Maya was chosen as she was the only person to have ever truly loved Sensei, and as a result was trusted to find a version of him that wouldn't fall victim to the weaknesses that pushed Prime down the path that led here.

The end goal of this journey is unknown; it may just be an endless quest to keep improving and creating a happier and more fulfilled Sensei until the end of time, or there may be a point where a final Sensei finally passes the test and is allowed to move on to something different. At this point, it's unknown.

It's also likely that this process is in practice across many parallel versions of the world. The version we occupy is Terminal 23, but presumably the other terminals are performing similar tests on their own versions of Sensei.

Ability To Reset
Although Maya is the only character seen to perform the reset, it's both told and implied that anyone can reset if they simply pray. Maya herself says that she is not the one resetting things, she is only asking God to perform the reset and the success is based only on her mental state and the willingness of God to listen. That said, Maya also says that she is responsible for ushering in the change of seasons and when considering adding more than twelve girls to the class she implies that she is somehow responsible for maintaining them through the resets. She also seems to get physically exhausted immediately after a reset, implying that whatever her "prayer" is, it's much more taxing than it may appear on the surface. In addition, Maya seems to get grumpy prior to each new reset, although this may be a symptom of her struggling to decide whether to bring Sensei back with her or not.

When Sensei suggests that he should perform the second reset, she suggests that all he would need to do is pray, although this may have been her humoring Sensei and knowing that he wouldn't be able to pull it off.

Although it's said that anyone can perform the reset if they simply pray, Ami in Trinity I says that resetting the world is something that she is not capable of doing. 61's dialogue in Tick Tock seem to similarly point to Ami not being capable of resetting. This may be related to Ami's seemingly unique status within the world of Kumon-mi, although there are other possibilities. It could be that Ami's personality makes her unable clear her mind and pray properly. It also could be that Ami is physically and mentally capable of praying for the reset, but that God is unwilling to listen. If the god in charge of activating the reset is Concerned (or some variant of Sensei Prime), it could be that he is off put by Ami's existence or status as a "replacement" for Maya in Sensei's life and as a result only listens to Maya's prayers.

Concerned vs Calm
The reset itself appears to be performed by the Wire God. When Maya actually activates the reset, the screen flashes up with the common "Incorrect Answer Chosen" screen which by all accounts seems to be an intervention by the Wire God/USER2 upon Sensei making a wrong choice. However the nature of the reset doesn't appear to be a "wrong choice" and from what we know of the Wire God it doesn't seem to be one to listen to prayers or make choices on it's own, it merely intervenes when it deems it necessary. In addition, Maya seems constantly obsessed with the sky and stars, which are frequently portrayed as being linked to the Concerned God.

It seems plausible that Concerned is the one actually listening to Maya's prayers and making the final judgement as the one "willing" to listen to her. When Maya prays to Concerned, he then triggers something in the Wire God to activate it's built in "Incorrect Answer" response to force it to reset back to the beginning of the loop. It's unclear if this is the intended behavior of the reset, or if it's being used as a workaround by the Concerned God which would imply that the resets are not actually designed into the system and may have been a later addition.