He was once in a relationship with Zoe Park until he caught her cheating.
During his middle school years, he once dated Meshi's ex-girlfriend and was considered the King. One day, he was excited to meet his girlfriend after school and hoped to meet her so he could give her a present. He tried to text her in a 'manly' way, asking if she wanted to meet. His girlfriend replied, saying that they couldn't meet because she had a curfew. Not believing this excuse so easily, he replied again repeating his question. Tae Sung looked up to see his girlfriend sitting with another guy across the park. He overheard their conversation in which they were insulting him behind his back and talking about how they should reveal that they're a couple.
Tae Sung, enraged at his two-faced girlfriend who cheated on him and her boyfriend (who pretended to care about him), punched both of them in the face. From that day onward, he had an inferiority complex around attractive guys and hated girls when it came to romance because he thought that they were shallow people who only care about looks.
He is tall with a chubby, yet buff, build. He has black hair and his hairstyle is a fringe up. Tae Sung is usually seen with a bored face due to nothing entertaining him, such as a fight. Most of the time, he is seen either looking down upon those who are weak or glaring angrily at males who are considered attractive. He has a signature scowl of belittlement and judgement on his face when being called out. Due to his large size, his neck is barely taper to give depth of his head to shoulder ratio.
Tae Sung is usually seen wearing a black tiger shirt with a loose white dress shirt and slim black jeans. Often times, he prefers not to wear his black shirt and leaves his dress shirt loose to expose the tattoos on his body. He has a tattoo of Buddha on his stomach and a carp on his right arm. His back and the rest of his body are covered with tattoos in a wing-like pattern.
After being rejected by Park Ha Neul, Tae Sung was heartbroken and trapped himself within his room for a long time eventually losing a lot of weight and became very thin. Thin Tae Sung is deemed quite attractive, as girls would stare at him in infatuation as he walked by. His tattoos looked different when he lost weight: his Buddha tattoo appeared as Gandhi, while the carp on his right arm appeared as small as a sardine fish. He did not maintain this look for long. Once he realized he was now attractive, he tried to use his looks to get to Park Ha Neul but was rejected again. This caused him to reason power and strength was greater than romance and binge eat his weight back.
Tae Sung is immensely powerful and strong, able to beat three upperclassmen who were twice his size. He has a tremendous amount of knowledge and experience when it comes to fighting. Tae Sung is powerful in all areas (speed, strength, technique and power), but his defense is most likely the most significant and distinguished factor which Tae Sung, as an individual, is overwhelmingly best at.
Tae Sung has a body that is perfect for any way of fighting he chooses, but focuses most on power and strength since his body allows him to deliver blows with immense strength. Despite his huge stature, Tae Sung is capable of moving at incredible speeds. He was even able to surprise Lee Jin Sung (a fighter well known for his speed) with a lightning quick tackle that won him the fight. Even a tactical approach which focuses on technique is possible for Tae Sung due to his experience in fighting. Best of all is his unbelievable endurance, which is one of the most impressive shown to date. Tae Sung was able to fight 3 of the Jae Won high's top fighters all in one day with no desire to back down. He is able to endure hard jabs and punches, seen when he took multiple shots to the face from Jin Sung without inflicting serious damage.
Tae Sung has exceptional knowledge over wrestling and demonstrated it in Chapter 125 when he tackled Jin Sung.
Being the bully of the series, he is a hateful person who will beat up anybody, including women. However, when he entered the animation department, he realized that he couldn't bully them because they all appeared to him as sheep, shown in Chapter 122.
Tae Sung has a narcissistic attitude and is accompanied by his large, intimidating stature. He is always shown as the leader in the group at his old middle school prior to Jae Won High.
Due to his hunger for blood and violence, he is known to transfer out of many schools.
Logan has a habit of not having people to look down on him, which makes him start up fights.
He has demonstrated his cruel behavior in Chapter 126, when he attempted to break Vasco's leg after getting him into a leg lock.
He has a hatred towards women and attractive men due to his poor experiences within middle school. Because of this, he has no sympathy in inflicting pain on either man or woman.
- After falling in love with Ha Neul, he loses 100 kg in order to impress her. He becomes handsome, but compares his muscles to a fish and a minnow. Kids previously bullied by him beat him up. When Ha Neul rejects him, he regains his weight, but becomes more violent than ever.
- He has an incredible sense of technique, that combined with immense power and size makes him one of the most prominent fighters in the story. Whilst he has held his own against the likes of Vasco, Vin, Jay, Daniel, and Zack; the only fight that he has presumably lost was against Goo. During the Stalker Arc, Goo was seen confronting him due to Lee beating up multiple seniors who were collecting money from the lowerclassmen students, which caused trouble to Gun and Goo’s business. Logan later stated that Goo almost broke his shoulder during their fight, and was seen with several bruises and marks on his face in the aftermath when Logan was told that he was transferring schools
- Logan has a similar appearance to Namor the submariner from the Marvel Comics