WARNING: The following contains spoilers for Season 4, Episode 20 of Haikyuu!!, now streaming on Crunchyroll.
Things aren't looking too good for Karasuno's volleyball team. At the top of Episode 20 of Haikyuu! To The Top, Inarizaki is up 13-7. By the end, they're forced to play the third set. After the first, it looked like Karasuno could easily pull off a victory here, and they do everything right in the second. However, the arrival of Inarizaki's Kita Shinsuke prevents any chance of a comeback from Karasuno.
Both teams have gameplans that are heavily focused on serves and targeting. Inarizaki's Astumu delivers jump floaters straight to Nishinoya, and Nishinoya struggles. Karasuno has a similar strategy. Coach Ukai planned to bring Inarizaki's ace spiker, Aran Ojiro to his knees on each serve. It was a masterful plan, and Karasuno could have caught up to Inarizaki. But Kita Shinsuke enters the game for Inarizaki and in some ways, he's scarier than anyone else on their team. It's his presence alone that captures the set for Inarizaki.
Kita is a very stoic and composed character. In his childhood, he was inspired by his grandmother to always keep a routine. That routine helps him establish confidence in his abilities. Anything he can do in practice, he knows he can do in an official match because he does it so much as part of said routine. Despite not getting to play until this year, pressure doesn't affect him. He is a key example of perfect practice and the execution of such practice. Therefore, when he's on the court, he doesn't let the pressure of the moment affect his teammates either.
He was brought on to the court in the latest episode to shore up his team's execution. As Inarizaki adds to their score, a collapse is more likely with the personalities present. The pressure to end the match quickly can cause mistakes. More importantly, they could start getting lazy in their plan by underestimating a team like Karasuno, easily demonstrated by their attacks on Aran. Kita is an enforcer. When he shows confidence, the team shows confidence in their abilities. Even if he isn't the best player, being the most confident one has immense power.
For Karasuno, this means trouble. Inarizaki provides mental reinforcements to their attacks. As the third set starts, Kita warns Astumu about going for spike serves and tells him to keep doing his jump floaters. He knows Astumu will probably still score with spike serves -- he has incredible talent after all. But Kita knows it's better for Astumu's mental performance to keep doing what works in case Karasuno is able to return the spike serve.
This match strongly shows how much mental strength affects volleyball. Karasuno fought through the audience's noise pollution, and Tanaka showed outstanding mental toughness when he pushed through targeted assaults in the first set. Now, Inarizai answers with Kita's presence. Karasuno wants to see Nekoma on the other side of this match; they can not afford to fall into a hopeless trap if they wish to win. The winner of the third set is not going to be won on athletic ability alone. It's going to be decided by which team can handle the mental pressure.