Hayato Gokudera - Tenth's Oath is the seventh Katekyo Hitman Reborn! Drama CD to be released. The story features Gokudera while torn between accepting the Ninth's promotion and going to Italy to support Tsuna or stay in Japan to be with him.
The story starts in the middle of the Sky Match, with Gokudera watching Tsuna fight Xanxus and unable to move because of Death Heater poison. As he watches, Gokudera remembers his fight near the end of Storm Ring Battle when he struggles to get Belphegor's half-Storm Vongola Ring. However, Tsuna shouts at Gokudera to abandon his ring as his life is much more important than winning, making Gokudera remember the vow that he made several months ago.
Several months before the ring battle, Dino had told Gokudera that Timoteo promoted him to become one of his six admins. Gokudera, at first, got excited hearing this. However, when Dino told him that he needed to go back to Italy if he accepted, Gokudera got angry since his boss is Tsuna, not the ninth. Dino then explained that all the glory he got for Vongola now will serve Tsuna in the future, making Gokudera hesitant as he also wanted to stay with Tsuna. Gokudera asked Reborn for suggestions, and Reborn told him to go since Tsuna didn't need him, surprising Gokudera. Reborn then came up with an idea; if Tsuna asked for Gokudera's help that day, Gokudera would stay and if he didn't, then Gokudera would have to leave. Gokudera agreed to this and went to Tsuna's house.
Tsuna wondered about his unfinished homework even though summer had almost ended, making Gokudera think that Tsuna would ask for his help to finish the homework, but instead, Tsuna just slacked off, frustrating Gokudera. Tsuna then noticed a cockroach in his room. Gokudera readied his dynamites to kill the cockroach, but Tsuna asked his mom for help, much to Gokudera's shock and disappointment. When the cockroach left the room itself, Tsuna asked Gokudera what's wrong and told Gokudera that he can tell Tsuna everything that he wants. Gokudera then explained everything to Tsuna about his promotion and expected Tsuna to be shocked. However, Tsuna congratulated Gokudera and decided to hold a farewell party. At this reaction, Gokudera decided to accept the proposal and go back to Italy in order to support Tsuna.
As he walked back home, he realised he had forgotten his dynamites at Tsuna's house and decided to get it back. When he was about to enter Tsuna's house, however, he spotted Tsuna and Reborn at the yard and overheard their conversation. Reborn asked Tsuna if he feels lonely now that Gokudera was gone, but Tsuna said that it becomes more peaceful without Gokudera since he's always scary and causing troubles, surprising Gokudera. Tsuna then continued, wondering if Gokudera has ever respected and thought of him as his friend instead of just the tenth leader of Vongola, reminiscing the times they've spent together and stating how happy he is because for the first time he gains friends, and from a friend's point of view, he doesn't really want Gokudera to leave, making Gokudera cry joyfully.
The next day, Dino and Romario waited for Gokudera at the airport, but to their surprise, Yamamoto was the one who came. Yamamoto said that Gokudera told him Dino would take him for a vacation to Italy and that Gokudera rejected the promotion. Reborn then commented that it was a good thing since Dino didn't need to assassinate Gokudera. Dino revealed that the ninth wanted to test Gokudera's loyalty towards Tsuna and had ordered him to kill Gokudera if necessary, though Dino had actually intended to help him escape. Reborn stated that he already knew it would turn out this way.
The story skips back to the sky match. Gokudera remembers his own oath and struggles to move, then finds that the Storm Vongola Ring has landed in front of him. Putting on the ring, he goes to help Lambo as he swore to help his friends, and declares that he's Vongola Storm Guardian and Tsuna's right-hand man.
- The Drama CD was adapted from Reborn! manga chapter 61: Promotion.