Sanzu Haruchiyo and Manjiro Sano

Mikey is usually a carefree teenager who loves to joke and play pranks around those he considers his close friends. He cares for them greatly and is determined to protect their honor. He rarely shows any sign of weakness, as he believes himself to be the foundation and support for Toman, and if the pillar himself were to display weakness, Toman would also be weakened.

As Toman's leader, his aura changes dramatically, becoming imposing and commanding. While Toman's members respect Mikey, they also hold a degree of fear towards him and his immense prowess. Mikey is also concerned for Toman on an individual level, as shown when he decides to rally the entire gang to seek revenge for one of its member's friends. Despite his imposing aura as Toman's leader, Mikey is still a child at heart. He has childish tendencies and loves to sleep whenever he feels like it.

The events that transpire throughout the story force Mikey to quickly mature. He is still an incredibly charismatic leader, but there is now an underlying melancholy beneath the surface. Indeed, within Mikey, there exists a great darkness. He is forced to carry the burdens of a troubling past, teetering between treading the right path and succumbing to that darkness. He usually hides this with his carefree grin. Without the right people to guide him, he becomes corrupted, turning into one of the most heinous criminals in the present. It is a large mission of Takemichi to make sure Mikey never veers off the right path ever again. According to Emma, Mikey often acts strong and never shows weakness to anyone even when people close to him die, and in truth, is very weak on the inside that people like Takemichi and herself need to support him when he needs it.

Even in instances where Mikey succumbs to that darkness, there are conflicting aspects of his personality and contradicting behavior. He is seen to be attracted to and seeking to embrace a life of violence, committing multiple atrocities or otherwise enabling his enforcers to carry them out without any apparent sign of emotional response, acting with indifference and a cold poker face, being even capable of hurting or even gunning down dear friends of his. At the same time, he tries to distance himself from his friends, likely knowing he won't be able to control his impulses, trying to separate himself from taking central command of his crew, and even going as far as attempting suicide as a means to seek both solace and a way to put an end to the chaos he helps create.

The central catalyst for this darkness is loss. As Mikey's loved ones either suffer or die, it affects Mikey on a very personal level, to the point he later claims their souls guide him[7], much to the surprise and worry of everyone present who question the veracity of said statements. Along with the increasing body count, Mikey's mental and emotional state deteriorates accordingly. Although he is still capable of acting composed and normal the effects of this growing darkness become more apparent even to Mikey himself. It is a result of this loss that renders Mikey vulnerable to manipulation and subsequently degrades his moral compass. In fact, in every timeline with a dark future, the cornerstone was triggered through the death of those closest to Mikey which allowed third parties to fill the void in his heart with evil.

As a teenager, Haruchiyo has a calm demeanor and rarely talks. He was extremely loyal and much nicer to those he follows and worships. However, it is later revealed that he is also quite manipulative and is exceptionally good at deceiving other people.

In his younger days, before meeting Yasuhiro Muto, he was described as a wild horse who couldn’t keep himself out of trouble. This made it quite difficult for other divisions in the gang to manage him.

As an adult, Haruchiyo seems to be more extroverted, blunt, and loud. He is ruthless and displays psychopathic tendencies.

Haruchiyo’s most notorious trait is his fanatical idolatry towards Manjiro Sano, believing Mikey to be his "king" (akin to the Chess King), and thus deserving of the utmost respect, loyalty and devotion. He is so inclined towards protecting Mikey or the image of him, that he assaulted a gang by himself when they were badmouthing Toman. He also approached Mucho when released from detention, purely to kill him for treason for betraying his king, going as far as brutalize him to his bones for his remnants to be left to be found afterwards.

In the present time he takes sadistic delight and notorious euphoria when executing traitors, while voicefully stating he is enacting Mikey's will. When encountering Takemichi, Haruchiyo ordered him to be silent for the "king" would speak, and threatened to shoot Takemichi for his casual approach, believing it a disrespect.