Mayonaka no Acchimono
Ahahaha - so the manga you couldn't find, then read this one instead because you loved this one, you found within this one! CRAZY Itsuho no Koiji! - So souless boy, is actually a berserker. Soul was eaten by his sword. Boy reincarnates. Finds his 'sword' again (next door neighbour) without realizing who/what he is. Current situation. Creepy demon guy conducting human experiments. Wants soulless boy. Baaaad move.
Akuma Game
OMFG SOMEONE TRANSLATED IT INTO ENGLISH! I CAN FINALLY FIGURE OUT WHAT'S GOING ON! FUCK YEAH. But it's still incomplete so sad. Waiting...
Silver Diamond
OMFG. I CRIED. (But happy ending so yay!).
Jigoku Meguri