"The last story is, love for the first time" - Main Movie Poster
「劇場版『THE LAST -NARUTO THE MOVIE-』の本ポスタービジュアルが解禁されました！！ナルトの赤いマフラーと横向きのヒナタ！？キャッチコピーコ ピーにも注目です！」
"This poster that's been lifted presents the visual theater version of ‘THE LAST - NARUTO THE MOVIE’!! Naruto’s red scarf and Hinata on the side??! Also focus on the text on the poster!" - Official Naruto Movie Twitter
「原作で描かれることなき空白の時、「THE LAST」 かって落ちこぼれと呼ぱ札た英雄、うずまきナルトの最後の物語は、愛。」
"The blank period not covered in the original story unfolds in “The Last”. A story of the boy who was once a (sidelined/left behind) dropout, the hero, the last story of Uzumaki Naruto is, love." - Naruto The Last: Movie Ad
"The Winter Festival is coming!
Ever since she was a little girl, Hinata wanted to give Naruto a scarf as a present, a personal gift from herself to him." - Naruto The Last: Movie Ad
"This movie if I were to be straight forward/blunt is about (romantic; ren'ai) love!" - Masashi Kishimoto
Ever since she was a little girl, Hinata wanted to give Naruto a scarf as a present, a personal gift from herself to him. Afterwards though, a mysterious figure appeared, with the malicious intend of kidnapping Hinata but ultimately doing so with the wrong person.
That person ended up being her sister, Hanabi!”
So that explains the matter of the scarf, along with the intended kidnapping victim.