Boukensha Guild ga Juunisai kara shika Hairenakatta node, Saba Yomimashita. The Comic

Synopsis

At just nine years old, Kiri leaves his sleepy village in the countryside and sets out to make a living for himself. With the help of a traveling merchant, Kiri reaches a bustling seaside town—where he's betrayed and almost sold into slavery. He manages to escape, but now he's all alone in the strange town with neither a roof over his head nor a coin in his pocket. The streets lead him to the Raging Kelpie's Tail, a guild of adventurers. Its colorful characters take Kiri under their wing and watch over the earnest boy as he overcomes challenges and grows both in height and spirit. (Source: J-Novel Club)