One Piece: Monarch Film.

He's what..?

With Ussop and the others:

"Robin! We been searching around forever! How about we take a break and we'll search Luffy in the morning?" Usopp said between panting as he sat on a nearby bench, Chopper sat down too, him too was also tired of walking and searching for Luffy all day.

"Yeah... and my legs are gonna give out." Chopper agrees as Robin thought about it. "I mean he wouldn't go that far right?"

"Chopper your talking about a guy who attracts trouble without knowing... and we're there to get rid of it." Usopp says as he slid down at the bench, his arms spread around the bench as Chopper did the same, Robin stands as she stand and think about it until something caught in the corner of her eye.

She look to see two black figures walking around the valleys, as she stares at them disappears into the darkness.

"But a good rest would give us more energy to search tomorrow, and I don't think you ever told us about this Imu pers- Robin? What are you looking at?" Usopp stops as he notice his archeologist looking at the dark alley. Chopper perks up to see what's going on.

"I think they know where Luffy is." She stated as she starts to run towards the dark alley. "Robin! What are you doing come back!" Usopp yells after her as he quickly got up along with Chopper. "Robin!"

"You know this gives me Déjà vu..." Usopp mutters skeptically, as Chopper tugged onto him.
"Come on Usopp we have to follow her!" He pleaded as the sniper took a second between going and find out what's beneath the darkness or stay and wait to his friends for come back.

"Usopp!"

"Oh okay! Let's go." As they both dashed to the dark alley.

With Robin:

She ran after the two cloak figures as she reaches into the alley, she looked around and senses taht they were above her.

"Gotcha." As she went into her stances.
"Miel Fleurs!" She exclaims as hands surrounds the figures as they fell, one grunted in a female voice.
Robin placed hands around their necks as in

"Grab!"

threatening to snap both of their neck.

"Ah—Robin!" The cloak figure says as she was cut off.

"Do you know anything by our captain, Monkey D Luffy? One wrong answer and you'll be dead." She spoke in a dreadful tone. The cloak figures shivered  one of the them protest.

"Wait-Wait! Robin it's me!" The cloak removed her hood to show an orangish-brown hair with big blue eyes, Koala and the other revealed to be a yellow fish men, Hack.

"Koala?" Robin asked as she lowered her hands and the hands around them disappeared. "What are you doing here? You almost made me snap your necks!" As Koala gulped at that thought, Hack spoke up.

"We're here for a mission, now what are you doing here?" He questions with his eyebrows raising up. As she was about to answer voices came abruptly behind her.

"Robin? Robin!" Chopper came first and behind him was Usopp, he had his slingshot in the action, but seeing Robin he lowered it down, Chopper stopped and look at the two people who were Koala and Hack.

"Robin!- oh." He look between the two people, one of them is a fish.

"Robin? You know these two?" Usopp looks at the two with confusion, Robin started to introduce them.