Just finished this manga.
It was really good I enjoyed it a lot! It has some shounen manga vibes that I love!
I really liked this story, but for me, there wasn't enough drama... I mean seishi really did a good job on this but had problems with emotional scenes and with epic too... I gave it 8, but honestly, I think It's 8,5. why not 9? I wrote that below

[SPOILERS]
The only disappointment was the final fight with Moki, the Final boss, and the final fight, it ended in an instant... yeah final boss was somehow satan, but still, I wanted more action and more epic and emotional moments! ofc final moments when Jim met everyone in his mind and defeated satan was very very good and emotional, but still, something is wrong for me, still not enough IDK if it's just me...
[END OF SPOILERS]

Although the manga is really good! very good story and rememberable characters that will fall in your heart
I will remember this manga. I really loved the characters and etc...
It deserves ANIME! make it happen! I recommend this manga to everyone who loves the shonen genre! especially if you love naruto alike shounens...