Volume 15

Volume 15 is titled "Straight Ahead!!!".

Cover and Volume Illustration
The colored cover has a red background. The title logo is dark yellow (fading from light), turquoise, and cyan, and the author's name is printed in turquoise.

On the front, an excited Usopp stands in the center with Luffy underneath him flying facefirst towards the reader. Behind Usopp are Dorry and Brogy holding up their respective sword and axe, and light blue close-up portraits of the two are shown behind each giant. The image has a gold border.

On the spine, Usopp is featured, and the skull logo is colored turqoise.

For the volume illustration on page 3, a profile of Luffy with a serious look on his face is featured.

Chapters

 * 127. Den Den Mushi (電伝虫): Dorry wakes up due to Brogy's weapon being blunt. Sanji impersonates Mr. 3 when Crocodile calls him, but Crocodile gets suspicious and sends Mr. 2 after them.
 * 128. Pride (Pirate Flag) (海賊簱): The Straw Hat Pirates head for Alabasta, and so does Smoker after intercepting their call.
 * 129. Straight Ahead!!! (まっすぐ!!!): Dorry and Brogy assist the Straw Hats in battling a giant goldfish and the two groups bid each other farewell. Later, Nami suddenly collapses from fever.
 * 130. Maximum Speed (最高速度): Nami attempts to shake off her fever and navigate to Alabasta, but Vivi decides that Nami needs a doctor first. They enter a winter area, when Zoro spots something weird.
 * 131. Tin Plate Wapol (ブリキのワポル): The Straw Hats battle the Wapol Pirates, whose captain, Wapol, can eat anything. However, Luffy manages to send Wapol flying away.
 * 132. See? (ね): The Straw Hats reach a winter island, but are attacked by angry villagers. However, the Straw Hats are welcomed after they bow in submission to the citizens.
 * 133. Adventure in the Country Without a Name (名もなき国の冒険): Dalton guides the Straw Hats around the island, revealing that the only doctor lived on top of a mountain and was inaccessible. However, Luffy and Sanji decide to climb the mountain with Nami on their back.
 * 134. Dr. Kureha (Dr.くれは): Dalton reveals that Wapol was once their king, but he ran away when a pirate named Blackbeard attacked. Unbeknownst to him, Wapol and his crew are nearing Drum Island. As Sanji and Luffy battle lapahns, Dr. Kureha comes down to a village to treat patients.
 * 135. Lapahn (ラパーン): Sanji continues fighting the Lapahns to no avail, while Dalton learns that Wapol has returned. Wapol intends to both take his kingdom back and get revenge on the Straw Hat Pirates.
 * 136. The Man Called Dalton (ドルトンという男): Dalton battles Wapol, but intercepts Chess' and Kuromarimo's arrows to protect the citizens. The Lapahns cause an avalanche on the mountain.

SBS Notes

 * Oda explains the "sailing ceremony" the Straw Hats did in Chapter 100.
 * The birthdays for Luffy, Zoro, Nami, Usopp, and Sanji are revealed.

ONE PIECE Preview! Grand reveal of the rough drafts!!
'''ONE PIECE Preview! Grand reveal of the rough drafts!!''' (ONE PIECE 予告！ネーム大公開！！) is an extra segment series that can be found in volumes between chapters, where a couple of pages from the author's rough drafts for the series are revealed. This volume includes part 17.

Part 17 (page 152)
This is a rough draft of page 9 from Chapter 139 of Volume 16. The final product looks nearly identical to this draft.

Usopp Gallery Pirates

 * Located on pages 172, 192, and 212-215.
 * Total number of fan submissions featured: 40 (+1 mailing address poster)

Grand Prize: A Hair's Breadth [紙一重] (Kyoto, Japan)

Volume Extras

 * Titled Coloring book segment [ぬりえコーナー], a self-colorable version of the cover for Chapter 107 is provided on page 48.

Trivia

 * This is the first volume to have an inside cover completely different from the outside cover, followed by Volume 19, Volume 38, Volume 52, Volume 56, and Volume 62. It features Pandaman sitting below a cherry tree, having some tea and rice dumplings by himself. There is also a yawning frog near Pandaman. Instead of Usopp, Pandaman is featured on the inside cover spine.