His real name was Kimishima Hisashi .
Amachi is later adopted by one of his relatives, who seems to be very wealthy. He also changed his name into Amachi.
A ruthless man who used money and violence to get what he wanted, he initially viewed his comrades as nothing more than mere pawns, though despite his value of underhanded tactics, Amachi is a fierce fighter and was one of the strongest Top Dogs in Town, he's also viewed as the most brutal among his peers
Amachi lived his life exactly as his father's last words. He cared only for himself and had little to no worries for others, including his comrades or followers. He is shown to be one of the most cold-blooded delinquent in Worst universe as seen when he attacked and beat up Butcher without any warnings or showing any facial expressions. He may easily injure his followers should he finds them useless or just annoying. It was due to his mistrust and the mistreatment of his followers that even leads to his eventual downfall.
At first, Amachi is shown to be cunning and not mind to gang up on people, as seen when he tried to gang up on Guriko. After receiving some criticism from his supposed-to-be-victim, he later developed a sense of honor, and had come to face all his opponents alone.
Amachi can also be seen as one of the most sadistic characters in Worst universe, as seen when he proceed to break Ozaki's arm though the latter was already defeated.
After his downfall, Amachi started to doubt his father's last words and seems to have started his whole life again except, this time, with his comrades. His character development shows greatly when two of his comrades, Gaga and Koumei, were beaten by the Manji grunts who came to town. Amachi fought them head on by himself for revenge.
Amachi shares a history with the Armament's Head, and Vice Head, Murata Shougo and Fujishiro Takumi, and while the details of this history are a little vague, whats known is that they all attended Kajiya Mid together and Amachi is the one who gave Shougo the scar on his face .
On the next day, he took out five of the last seven competitors. He made Adachi Daigo and Yumita Tomohiro his lackeys, and before ordering Yumita to attack Tsukishima Hana, he stabbed Adachi's shoulder with a sharpened pencil.
After beating Yumita, Hana went after Amachi.
After his defeat , Amachi quit Suzuran.
Amachi would later join Rindow High and start his plan on conquering the whole city from there, first taken on the schools near that were part of the Kurotaki Alliance.
He started hiring mercenaries to work for him, forming the Amachi Army.
After losing to Hana a second time during the war between their respective factions , Amachi's attitude seems to change towards his comrades, this was first seen when he showed up alone to confront the Kawauchi Group for beating up Gaga and Koumei.
He later accepted Takumi's request of participating in the War with the Manji Empire but later admits to Shougo that he just wanted to fight Manji's strongest guys and that he still considered all of them his enemies.
Amachi is one of the seven men who traveled from Toarushi to Machida, Tokyo to finish the war against The Manji Empire's Manji 7. He is the last in attendance and he defeats the Zento Group's Higuchi Shuuji .
Amachi was last seen leaving Machida, Tokyo with his inner circle from the Amachi Army, and Amachi himself considers them his only friends.
It's unknown what became of him, or his group after the final battle with Manji.
Fighting Prowess & Strength
Amachi is on a similar level of strength to Hana and Guriko, and, as a result, is one of the strongest delinquents in the Worst universe. Several facts and incidents that could be used as measurements for his strength are:
- He is one of few people in Worst who has fought on par with Hana.
- He is the one and only who got in a fight with Guriko and came out with no visible injuries . This, however, was due to Guriko accidentally falling off of the balcony, but it was shown that Amachi is capable of fighting on par with Guriko.
- He easily overpowered more than half of the Freshmen War contestants and scared them to the point of doing whatever he told them to.
- Upon his arrival to Suzuran, he defeated Butcher, one of the strongest sophomores without much difficulty .
- Along with Hana, he is shown to make the most improvement as he becomes much stronger after each fight.
- Defeated three straight Manji Empire faction heads, with the final two sustaining and overcoming injury.
- Amachi vs. Ozaki Kenichi - Won 
- Amachi vs. Butcher - Won 
- Amachi vs. Oosugi Naoki, Hashimoto Keita - Won 
- Amachi vs. Yumita Tomohiro, Adachi Daigo, Inose Hiroshi - Won 
- Amachi vs. Hana - Lost, twice  
- Amachi vs. Doumoto - Won 
- Amachi, Kuroiwa, Maezono, several underlings vs. Guriko - Lost 
- Amachi vs. Shinkawa - Won 
- Amachi vs. Fujishiro Takumi - Won 
- Amachi vs. Daitou Takashi, three underlings - Won 
- Amachi vs. Sera Naoki - Won 
- Amachi vs. Guriko - Won, Guriko tripped 
- Amachi vs. Okuda, several underlings - Won 
- Amachi, Daitou, Ichigo, Ichie vs. Nakamori Shouji, nine underlings - Won 
- Amachi vs. Jouseki Kimiaki - Won 
- Amachi vs. Higuchi Shuuji - Won