Tensei Youjo.: Shinjuu to Ouji to, Saikyou no Oji-san Youhei-dan no Naka de Ikiru.

Upon awakening, a little girl named Lezay finds herself standing alone in an unfamiliar meadow. In front stands a massive dog. Such a creature had never been seen near home before. At that moment, a conclusion forms that this must be what is called reincarnation into another world. Soon, a band of muscular mercenaries appears, seemingly on a mission to subdue the giant dog. However, it turns out this dog is no ordinary beast, but a divine beast. The divine beast, Ranag, becomes deeply attached to Lezay, the only one it can communicate with. In response, leader Alragia offers to take both Lezay and Ranag under the protection of the mercenary troop...? A little girl, a divine dog, and a mercenary squad. This is a bizarre off-world fantasy with some strange members!

(Source: Alpha Manga)