Hinata begins to walk faster.
“Lesson numb-ber three: Re-emeber the mission objective in every action”.
She began to perform an even greater number of hand signs than before in rapid succession
“Summing Jutus!” she finally yelled.
A large plume of smoke ruptured from the lake.
A large lizard appeared on the lakes surface. The animal was as large as a cow.
With a flick of its tongue and the movement of its eyes, it suddenly becomes obvious this is a chameleon.

Hinata stood top its back.
“Allow me to introduce you to Kamereon”
Hinata jumped of its back and landed behind it.
“Please do not allow them to follow me” she requested.
She whispered “Don’t h-hurt them,”
Kamereon nodded “Right boss”
It took a ready stance as Hinata began to make her get away across the body of water towards a densely wooded area.
Quote:
Where did Hinata get a chameleon contract?
From a mission in the anime!
Shiromari is a chameleon summon that takes the form of a castle. It was summoned over fifty years prior to Naruto's visit to the castle with Hinata Hyuga and Kiba Inuzuka in the The Cursed Haunted Castle filler arc. As a last resort, the dying lord of the castle summoned Shiromari and had it devour anyone who approached. The lord died before he could release the summoning, and thus it remained bound to the contract scroll used to summon it. From then on, it devoured anyone who came close. During a mission to find a group of missing people, Hinata, Kiba, and Naruto stumble upon this summon. After being swallowed by it, they realize just what it is. While attempting to find the contract scroll that is keeping it summoned, the spirit of the castle lord appeared and led them to it, because the lord felt sorry for the creature spending fifty years guarding his castle, and wanted to set it free. The summoned creature is very loyal to his summoner, having protected his summoner's castle for so long. Naruto cut the scroll into pieces to send the summoned creature back, and escaped from the body of the summon with Rasengan. The anime does not show Shiromari's true form, but instead, a picture.
It is not shown in the anime, but I don’t think they would have left the summons contract behind. I’m assuming what was left of it was collected at a later date and reconstructed as it is valuable. Here Hinata was able to sign the contract as she was on the retrieval mission. Her blood line limit helping in finding all of the pieces. She also would have used it to help them piece it back together. She was also responsible for suggesting retrieving the scroll.