LeeSaku

LeeSaku is a Het ship between Rock Lee and Sakura Haruno in the Naruto series.

Canon
Rock Lee developed a crush on Sakura as soon as he met her for the first time. He approached her and asked her out to which she bluntly rejected because she found his appearance to be disgusting. In the Forest of Death, Lee decided to try and catch ten leaves before they touch the ground. He declared that Sakura would marry him if he succeeded. Lee caught nine leaves but noticed a squirrel with an explosive tag on it. He began to worry and followed its trail while leaving the tenth leaf to fall.

Lee arrived to see Sakura under attack by three Genin from the Sound Village. He vowed to protect her until he died and put up a fight against them which impressed her. After the fight, Naruto woke up and insulted Lee which prompted Sakura to smack him for being rude. Lee felt a little down about the fact that he could not protect Sakura and vowed to become stronger.

Lee was later brutally injured during his battle against Gaara and told that his days as a ninja were over. Sakura felt bad for him and decided to visit him in the hospital along with Ino. When they arrived, they found that Lee had gone outside to train which worried her. Sasuke eventually left the village and Lee saw Naruto give her the nice guy pose when promising to bring her back. This inspired Lee to leave and help as soon as he recovered from his surgery.

Over two years later, Sakura and Lee are both on the same mission to rescue Gaara. When Lee was fighting a clone of himself, he thought of how strong Sakura became which inspired him to beat the clone. When heading to the Five Kage Summit, he witnessed her confessing her love to Naruto which caused him to give a look of shock and jealousy. During the Fourth Shinobi World War, Lee was caught in the Infinite Tsukuyomi and dreamed of Sakura squealing over him.

Fanon
LeeSaku is a fairly popular ship in the Naruto fandom. It is not as popular as NaruSaku or Sasuke but it still has a rather large amount of popularity. This ship is mainly popular due to Lee's crush on Sakura as well as Sakura's growing respect for Lee. It is often shipped along with NaruHina by those who would rather not see Sakura with Sasuke. LeeSaku usually rivals the NaruSaku, SasuSaku and LeeTen pairings.

Trivia

 * Lee and Sakura were meant to symbolize human weakness at the beginning of the series.