If anything is the most enjoyable part about of this manga, it is the protagonist. He uses his wits and reminds me of both Keima from TWGOK and lelouche. He notices he most minuscule of details and uses his rhetoric to convince others to act a certain way.
Also the premise is quite fun, and more details should be elucidated along the way ( there is a simple motive but there is probably a deeper theme ). I personally like these stories where a protagonist has a goal like this as it prevents the author from requiring girls falling from the sky, a strong bond from the past or something. Sure, it isn't the most effective means but it certainly isn't awful.
The art? Fabulous. Each character is drawn beautifully, as fitting for a story that isn't focused on fighting or comedy.
Enjoyment. I thoroughly enjoyed it. The psychology is really good as well, though I doubt its effectiveness in reality ( try it! ). It teaches you to notice that someone had a little thing going on yesterday or how to coerce your friend to make you food ( now this is gold. I saved it to my photo album ).
If you are seeking what this manga offers, you will be impressed at it. However, it is by no means a detective Conan.
key words- search, imouto, psychology, father, debt, several heroines
