I don't know quite know what Yamada was going for with this series based on the first volume, and considering it was originally serialized online, maybe he didn't either at first. The story starts with Almark, the protagonist, being the five year old son of the vice-captain of a famous company of mercenaries. His father doesn't believe he has the temperament to be a lifelong mercenary and wants him to attend magic school, for which the usual enrollment age is nine years old. Circumstances dictate otherwise and at eight years old Almark kills two mercenaries in combat. Soon after he's on the battlefield with the rest of the company and would kill many more over the course of a year. After a near-death experience, his father forces him to leave and Almark begins the nearly two year long journey to the magic school alone. There would be much sorrow and hardship and he'd be forced to kill many who betrayed him along the way. That's the prologue, about 7% of the book, which isn't all that long, so a lot is told in summary.
I've presented this all for the purpose of asking a question. Knowing only what I've written here, what kind of character do you think Almark is? This is told from third person, so it's difficult to know for sure, but he seems unfazed by it all. Almark is arguably absurdly stoic and only ever seems to experience post-traumatic growth. To say he's precocious would be an understatement. Honestly, it's rather strange. It really makes me wonder what kind of character he'll become. Then when gets to the school he readily integrates with his classmates and able to get along with others. He could even be described as having a warm and compassionate personality. I don't know if it later changes, but I was surprised that his school life was almost entirely typical everyday stuff. Almark's goal is to become a great mage who can return to his homeland and bring an end to all the suffering he possibly can.
Again, I must reiterate how different of a character Almark is from usual sort in these circumstances. The usual sort is based on rage and possibly PTSD. Some examples would be: Red Rising, Will of the Many, Berserk, Vinland Saga, and Attack on Titan. The closest, though still not a good match, I can think of at the moment to relate him to would be Shimazaki from Shimazaki in the Land of Peace, which is a strange comparison to make.
Further confusing matters to me, the manga adaptation is seinen not shounen, which means it's marketed to men. The first volume of the manga only covers a bit more than a 1/4 of the first light novel volume. That seems slow to me considering that there's not all that much substance so far. There's potential here to go somewhere interesting, but I don't yet have the confidence that the author will able to take it there. I'll be reading them as they release to find out though.