In the Loguetown Arc of One Piece, major characters include Monkey D. Luffy, Roronoa Zoro, Nami, Usopp, and Sanji of the Straw Hat Pirates. Other new key characters introduced in this arc are Vice-Admiral Smoker "The White Hunter" and Captain Tashigi. Other notable characters include Bartolomeo, Gol D. Roger, and Ippon-Matsu. This arc takes place right before the Straw Hat Pirates enter the Grand Line.
The primary reason being that the crew visits Loguetown, the birthplace of Gol D. Roger and execution site, as a final stop before their grand adventure. Loguetown, also known as "The Town of the Beginning and the End," had historical importance in the world of piracy and a strategic location as the last major port in East Blue before entering the Grand Line.
The plot of Loguetown Arc becomes unravelled as the Straw Hat Pirates finally get to the historically significant town. Everyone has their own agenda in the crew: Luffy wants to view the execution ground where Pirate King Gol D. Roger died; Zoro tries to acquire new swords; Nami searches for a tool to help her navigate the voyage into the Grand Line; Usopp is trying to obtain equipment to improve his shooting abilities; and Sanji tries out the local market, searching for a special ingredient. The Straw Hat crew has to meet with a range of obstacles and enemies that predict the great adventures awaiting them in the Grand Line as the crew members work towards their respective goals.
On his way to the execution ground, Luffy finally reaches the execution platform, which Gol D. Roger once stood. The scene is cut just then by the surprise appearance of Buggy the Clown, a recurring rival who tries to execute Luffy the same way as the former Pirate King did. This dramatic confrontation tests Luffy's resolve and unravels his resolution before death, exactly the way the legendary smile Gol D. Roger had during his execution.
The arc also introduces the powerful Marine Vice-Admiral Smoker, who consumes the Smoke-Smoke Fruit to make him one of the long-term pursuers of the Straw Hat Pirates. His presence in Loguetown adds a new level of tension to the story by having a cat-and-mouse chase with Luffy around the town. The chase will not only showcase Luffy's elusive abilities but also cement Smoker as one of many recurring villains to pop up through many succeeding arcs of the story to annoy the Straw Hats.
The Loguetown Arc marks the serious development of characters as well, mainly Zoro and Usopp. Zoro is in search of new swords; he ends up getting the cursed blade Sandai Kitetsu, portraying his talent in swordsmanship and his good luck. Usopp's past is further revealed in a flashback of his father, Yasopp, explaining how emotional their relationship really was and just how tough it had been for Yasopp to leave his family to become a pirate.
Just as the arc starts reaching its climax, a fierce storm runs through Loguetown, making a panic that permits Straw Hats to escape from Smoker and Marines. This storm is later identified to be the work of Monkey D. Dragon, Luffy's father, adding mystery to the plot and giving an indication of the fact that there are more global changes occurring in One Piece.
The Loguetown Arc ends with the Straw Hat Pirates finally able to get away and head toward the Grand Line. This departure marks an important turn in their journey, as it is one from the comparatively peaceful East Blue into the unpredictable and dangerous waters of the Grand Line. The events in Loguetown will prepare the crew for the trials that await them, both physically and spiritually. It makes for a very compelling bridge between the East Blue Saga and the following adventures, setting the table for the epic journey lying ahead for the Straw Hat Pirates.