Welcome to the second decade of 21st century where every other series somehow has an MC who gets teleported to another world where is he/she is either reborn or swap bodies. The land where he/she is now is full of magic. There is mana, there are elves, dwarves, shamans, lizardmen, goblins, spirits, faeries, insert-any-Tolkein-fiction-character or trope etc. Our MC somehow retains memories of his/her past life but doesn't really cares because he/she was either a loser/hikikomori or a wage slave and is now really excited with the prospect to explore this brave new world. He/she is open to challenges that this new world awaits but there is one catch- our MC is very powerful and by powerful, I mean his power level far exceeds the geniuses of this realm. Nevertheless, he still decides to join a guild/school, form his own adventuring party and explore new frontiers. Throw in some beautiful girls and now he has his own harem.

Gentlemen, this is what Kenja no Mago is about (minus the harem part). This series has nothing new to offer and is what I would call, 'the most below average isekai' series out there. It's the shovelware product of manga world where the author decides to throws in a bunch of character tropes with a rinse-and-repeated plot in a giant cauldron, stirs it and ends up with this as a finished product.

Story - 1/10, Character - 1/10

Can you read and write? Do you know what isekai is? If yes, congratulations, you can easily conjure a plot far better than what this manga offers.
Throw in an insanely overpowered protagonist, an evil lord creating an equally evil army, a kingdom, a bunch of classmates as your party member and you get KnM. Our characters offer nothing good in terms of personality, just another recycled shounen trash. If there is a pandora box of cliche out there, then it was possibly opened during this series' inception.

Art- 6/10

Just average; nothing new, nothing groundbreaking.

Enjoyment- 3/10

I don't think I can give a point above 3. This manga is honestly suited for those who want to get an introduction to the isekai genre and can even act as a foundation for their entry into the world of fantasy manga.

Overall- 1/10

Self-explanatory. If you are someone who has been reading manga for a long time, you will chuck this one to the bin.