Both are exciting reads for me personally because they have a lot of science behind it. So you'll frequently find plenty of technical information in it that makes sense in theory but probably wouldn't work in real life. But then again, since when do we look at real life in manga? ^^
Created by same author, Index and Heavy Object appeals to sci-fi and experimentation that extends beyond imagination. Both series' main male protagonist also has similar personalities and often gets themselves into events that has their life in jeopardy. Throughout both series, we also learn more about the many complicated mechanics that revolves in their world. These have great impact on their society as well as their past, present, and future.