This guide will show you all the most important steps to complete this SEGA masterpiece avoiding excessive spoilers and mentioning only the necessary. I remember that the secondary missions that you can undertake during the game are not reported given their high number and their easy resolution.
Chapter 1 - The fate of a traitor
After the opening cutscene you will have to follow your adventure companion up to an alley to get to your goal and recover the money you owe: as soon as you cross the door, after pressing X, your first battle will start which turns out to be a tutorial; follow the instructions to complete the battle and learn the basics of this game. When you have defeated everyone you will recover the briefcase and you will have to take it to the Serena, a nearby bar. Follow the red dot and when you are in the main street, where you started the game, a cutscene will start and you will have your first real battle. Another movie will follow that will highlight your personality. When you can go to the back and approach the stairs to start a cutscene in which you will meet Reina and Nishiki and then Yumi. You will find yourself taking possession of Kazuma the next day and you will have to bring the briefcase to the Fuma family office: on leaving you will meet two other people and to reach the office you simply have to continue towards the red goal on Tenkaichi street. In the office, on the desk, you will find the first save point, a telephone, after which the only thing to do is to enter Mr. Fuma's room to deliver the suitcase. During the movie you will receive a phone call and you will be forced to go north to the theater to resolve the situation: unfortunately you will be stopped by a group of henchmen who will tell you to hand over some money, which you obviously don't have. Hirata, the principal, will unleash his friends on you and a battle will start that turns out to be quite easy: a few shots and they will all fall to the ground running away with their tails between their legs and you can reach the theater square. Enter the building for another cutscene. The scene will not be the happiest but once again the charisma of your digital prosthesis, Kazuma, will stand out.
After several cutscenes you will have to fight against some inmates who are having lunch with you: your main target is the inmate whose energy will be marked at the bottom right, but to make the situation easier for you it is advisable to defeat them all before moving on to him: the difficulty of this battle consists in the fact that your opponents will use the objects present in the area a lot, exclusively chairs, and these will damage you enough during the fight. After the battle, you will be asked to save.
Chapter 2 - Ten years later
Shintaro Fuma is the first name that will appear in the second chapter before your eyes: after ten years you are free to get out of prison. When you are on the road you will have to reach the Stadust: the red box on the left indicates the presence of a shop where you can buy food and a rope that will give you an attack +10: continuing north at the T-junction, you will meet Abe the hooligan: the clash will not be anything special, you can try to use your rope if you bought it, but don't expect a great functioning from it. A few hits and Abe will fall to the ground leaving you free way and telling you that the best informant on the square is Aoki and he is at the Theater Square: going there you will be stopped by a martial arts student who can teach you something about fighting, after which he will deliver you some notes and you can continue towards the square. You will find Aoki dressed in orange halfway down the square and he will give you some information, some sad, some important: he will tell you how to get to the Stardust, so reach him following the objective on the map. As soon as you get there Yuja will challenge you to avoid entering the club. He has a strong frontal attack and will head into you without too much trouble, but you are much faster than him with punches so use the strongest combos you have to defeat him immediately: you will then be invited to enter the bar, go up the stairs and watch a movie. You will learn about the murder of Sera, the man who had expelled you from the family: the movie will however be interrupted by the arrival of some people on the ground floor of the club. Go to them and talk to one of them to start another cutscene: the loan sharks will ask the owner for money and you will obviously do everything to avoid this happening. Defeating Takahashi and his companions will not be difficult, just help yourself with the objects in the surroundings and use the Power Kick if you have already unlocked it among the upgrades. In the following video you will see your old friend return. When you're okay, talk to Shinji and tell him you're ready. You will be asked to save.
Chapter 3 - Chaos at the funeral
The opening movie will not be the happiest, at least from the point of view of cruelty. First, as soon as you have taken control of Kazuma, you will have to attend the funeral, which is slightly difficult as the guards will kick you out of the factory on the first misstep. Avoid the main road where there are three guards difficult to spot, then go to the parking lot on the right paying attention to the two guards who follow, luckily, a specific road: pass behind them when they come towards you and turn right at the first turn to find yourself near the stairs of the main road. On the right, talk to the man in black behind the counter with the white curtain to sign: use a false name and say you were a member of the Dojima family. Enter the building and talk to the man at the counter on the right to find out he lost his badge near the reception, then exit the building and go right to find something that glitters on the ground - grab it and go to the far left to follow the red arrow. When you are close to the target you will be attacked by Yasuda: use the dodge (R1 + X) to avoid his blows and hit him from the back to make him fall in a short time and without too many problems. Then continue inside the building where you will find Shinji: follow him to a room where you will have to wait and here you can also use a phone to save the game; as you go up the stairs with Shinji, however, you will notice a man with a green indicator on his head who takes the role of a street vendor. Look at the pictures on the wall near the door and when you're done, a cutscene will start. You will have to fight against a group of henchmen who are not very dangerous but will be helped by the objects in the room that you throw at them could hurt you enough: near the table, however, there is a potion that will come in handy shortly since, once you have escaped this danger you will jump out the window and there will be several armed men making war on you. On the right, in a door, you will find two forbidden swords with a duration of 15 blows and you will have to face all the men present in the area marked with a yellow dot. After the first horde some of them will come out from the door on the right, while on the left you can find, near some spears, a potion: defeat the second horde, enter the door from which they came out and continue towards your destination, always marked in red, defeating various enemies. You will then find yourself in the room where the coffin of the deceased is kept and you will have to continue towards the opposite wing of the building going up the stairs: on the left you will find, at the end of the corridor, a dead end, a potion, while on the right the road to exit. Go down the stairs and under one of them, on the left, you will find another potion, now then go out and you will find yourself in the parking lot of the Tojo clan headquarters. Last but not least, after yet another horde of enemies he will throw himself against Futo: strong but slow beast, you just need to dodge his shots every now and then and then hit him from behind, but avoid getting too close to him otherwise his lethal moves they will be truly lethal. If you need to, on the right of the gate, near the white curtains, there is a potion.
Chapter 4 - The meeting
You will be saved by Date, an old acquaintance of Kazuma's detective. You will need to reach the Serena, illuminated on the map. After the movie your mission will be to go to Bacchus, and you will also be introduced to the function of the Lair. You will then receive a call from Yuya inviting you to watch his girlfriend's show: it will be marked in green on the map. Reach him to watch a movie and then you will be asked to attend the second show too, do it to take part in a fight: the hitman has a fairly powerful firearm so be careful and try to dodge as often as he will aim the rifle against. He also has a lot of energy so it will take you a while to kill him: avoid taking objects in the room as they will only slow you down and put you better under your opponent's aim. Exit the room and follow the green arrow to reach the room where Yuya and his better half are held hostage: defeat the henchmen paying attention to their leader, armed with katana. Eventually you will receive 3000 experience points and a card for free entry to the strip tease salon. Now you can go to Bacchus. You will meet a little girl, fundamental for the story, and with her you will have to carry on the chapter: on leaving you will have to face thugs who beat a dog and then arrive at a shop that sells dog food. The shop is located on the second street from the bottom left of the map. Return the dog food to Haruka the little girl and feed the dog after which the little girl will rejoin you and you will receive a call from Date. You will have to go back to the Serena: on the way you will be stopped several times by some gangsters from different families. As soon as you arrive at the Serena you will see a movie and then you will have to go to the Ares: then follow Haruka and when a policeman stops you always answer with the first possibility; when you arrive at the Millenium Tower continue to follow Haruka to the elevator. A battle will start against a boss and his followers: it shouldn't give you much trouble except for the fact that your opponents have a lot of energy and are very resistant. Help yourself with the sofas in the room and the situation should be resolved without excessive complications. You will be asked to save.