I'm lucky enough to have this series licensed in my country and, boy, it is such a great read! I keep re-reading it lots of times. The characters and story are well-written, and the amount of detail put into the story and artwork is amazing. I'm not saying the artwork is very detailed like in, say, Emma, but the artist put thought into drawing the smallest details so it all fits.
The 2 main characters are fleshed out well, each with their own problems and strengths. Koreeda is a genius hacker who used to do illegal cracking until he was found by Sakai, an angel investor who then took him under his wing to "raise" him (not in a weird way, but as an investment). Sure, Koreeda is very OP, but his emotional baggage and crippling social anxiety are nothing to scoff at and really makes him feel more human. Sakai may seem like only a calculating, clever, rich businessman, but he has instances when he doubts his way of working, which has caused other people under him to come into harm's way. He shows a lot of tough love to Koreeda, who is inept at basically everything except programming and laundry (which he excels at because he was often bullied at school, poor baby ;_; ) , and he's the anchor and the one who helps Koreeda find his purpose in life by utilising his ability for good purpose instead of using it for cracking as a means to take revenge against the world, which Koreeda felt didn't understand him. The supporting cast are also mostly very likable, bar the few main antagonists such as a couple of crackers and a sly higher-up at the police department.
The story follows Sakai and Koreeda as they solve cybercrime cases, sometimes with their lives on the line. They dealt with ATM cracking by a rogue cracker, money laundering using thousands of bot in an online MMO, and, in my most favourite case yet, infiltrating a deep web to catch the users and admins (volumes 6-7, though I must warn you that the 7th volume contains
scenes of Koreeda being tortured).
. The other characters add a layer of richness to the story; we get to see them acting naturally in scenes without feeling forced or scripted, and they have distinct personalities and some smarts as well. The dialogue reads smoothly (except for maybe Koreeda, and thank goodness we have Sakai able to translate for us XD) and, again, doesn't read like it is from some script or badly-written anime lines.
I hope I've explained it clearly... But definitely give this a read!