Reducing opacity is not the same as making him blend. you've ghosted things that shouldn't be, like the tree in the foreground, unless that was your intent. if that's how you want it to appear, then it's composition is acceptable. but i would add a subtle gradient on kenshin, making him slightly darker on the bottom.

otherwise, the same coloration and blending can be achived with full opacity images. it's just a matter of patience in playing with the colors, and making subtle adjustments with the various tools, namely; paint brush, blur, and smudge tools. if you know how to burn and dodge, then use a the method found in this tut. if your not sure how to burn and dodge, don't try it. it's something that can completely change your picture, but in the wrong hands changes it for the worse.