Natsu Dragneel, Lucy Heartfilia & Romeo Conbolt vs. Dan Straight & Coco (Earth Land)

 is a fight that takes place during the Key of the Starry Sky arc.

Prologue
While searching for the clock part in the cryptic ruins, Natsu's group is approached by Dan and Coco of the Legion Corps.

Upon seeing them, Lucy hides herself behind Michelle while Natsu speaks out to them. Dan explains that they know about the contents of the book, "Key of the Starry Heavens", therefore, they are aware that a clock part is within the area. The male Legionnaire is briefly distracted by the appearance of Lucy, at least until Natsu goes on the offensive with Dan.

Battle
Natsu attacks with his Fire Dragon's Roar, intent on getting payback with Dan, though his technique is easily repelled by Ricochet. The flames instead attack Romeo, Michelle, Lucy and Happy. Natsu continues to fight, however, and begins destroying most of the ruins with his Fire Dragon Slayer Magic.

Natsu and the others make use of this situation by fleeing the battlefield. However, they are again confronted by Dan and Coco. Dan attempts to speak with Lucy about love but is told not to by Coco, who reminds him that their goal is to find the clock part. He states he knows that but love is very important also; afterwards, he does his infamous love quote and poses. This annoys Natsu who then goes to attack Dan again; his attempts, like before, only end up hurting his teammates more so. Dan says that he will slice anyone who interferes with love and goes to attack with Habaraki, though ironically, his only victim is Lucy who gets shrunken down to doll size.

Dan tries turning her back to normal, but upon realizing she can pose on his desk when he goes home, decides against it and ties Lucy around his waist. He then goes back to fighting Natsu using Habaraki and tells Coco that she can go look for the clock part on her own. However, she argues that she can't without his help. A similar issue is found within the group of Fairy Tail Mages.

Dizzy from being thrown around while attached to Dan, Lucy summons Sagittarius, but sadly, he is also shrunken down to the similar state his summoner is in. Nonetheless, Sagittarius tries to help but is unable to do anything, so he leaves, disappointed in himself.

Suddenly, Michelle has an idea and goes to Dan. She suggests that he marry Lucy right then and there, adding that they're in a "holy" place, which makes the situation even more perfect. Dan is very pleased with the idea. This distracts him long enough for Romeo to go under and use his Yellow Fire technique before Dan, causing his armor to stink heavily. While moving around irrationally from the smell, the string Lucy is attached to breaks and she is caught by Romeo's Purple Fire; afterwards, she hops on Happy and both fly away. Dan chases after them and attacks with his Habaraki once more, landing a direct hit. Lucy is returned to her normal size but Happy grows several feet tall. Because of his inability to move normally, Happy starts destroying the ruins and steps on Natsu once more. Dan turns him back almost immediately afterwards, however.

Natsu and the others regroup to look back on the book by Will Neville for clues relating to the clock part. Seeing use for the written piece, Coco tries to obtain it. The others start running away, with Coco chasing after them, but Natsu stays so that he and Dan can fight. While running away and reading the book simultaneously, Lucy rams into an angel statue, setting off a trap that causes her and the others, including Coco, to fall through the floor. They manage to cling onto the rocky walls for safety. However, Lucy falls off her ledge, along with Coco, and both fall to the bottom.

Aftermath
Lucy and Coco decide to go look for the clock part on their own at the bottom of the pitfall, while the others go back and search also. In the meantime, Natsu and Dan begin their own personal fight.