Ok yea I read the first 5 chapters of the manga because the original novel is by Ono Fuyumi who wrote 12K, and I read the novel because
it was two bucks at book off the manga was pretty interesting

Non-spoiler portion:
Favourite characters:Toshio 尾崎敏夫
Natsuno 結城夏野
Ritsuko 国広律子
The Mutou family 武藤一家
The Tanaka siblings 田中姉弟
Other characters I liked:Tatsu (the old woman at the stationary store) 竹村タツ
The nurses @ Ozaki Hospital 看護婦たち
Seishin's parents 静信父・母
Kanami 矢野佳奈美
Sunako 桐敷砂子
Least favourite characters:Seishin (I'm sorry but seriously - -) 室井静信
Motoko (if that's how one pronounces her name) 前田元子
Atsushi 大川篤
Click for spoilers:
Favourite couples/combinations (?):Megumi + Masao 清水恵・村迫正雄
Tooru x Natsuno 徹夏!!!
Tooru x Ritsuko 徹律
Natsuno + Akira + Kaori 墓堀トリオ
Natsuno x Aoi or Natsuno x Tamotsu ナツ・葵 or 夏野・保ちゃん
Toshio x Seishin 幼馴染
Toshio x Chizuru 敏夫・千鶴
Saddest/most unfortunate incidents:Yada mother & daughter (TT_________TT) 矢田妙・佳奈美
The temple crew (TT_________TT) 寺の皆さん
Akira's death (TT______TT) 田中昭
I think the major difference between Shiki and 12K is the way things end...by the time I finished the last volume of Shiki I was like...major orz....

whereas 12K always end in a somewhat "good" manner lol... I guess that's the difference between horror and fantasy eh? (not the point)
In a way, I wish Seishin and Sunako would've died in that fire at the end, but that would've lost the reality and theme of the entire novel, maybe lolOverall the main theme of the story seems to be the interaction between human, death, and human nature...it was interesting how there were so many characters, each of whom had a different view on the entire matter...personally I had to side with the humans instead of the shiki, despite the fact that many people (innocent ones included) were killed by humans in bloody ways...no matter how human the shiki are, I think it was a mistake for Sunako and Tatsumi, etc to think of creating a village full of them to begin with...

Point of view wise, I think I agree most with Tatsu and the Mutou family (in terms of having the courage to run away from the village they've always lived in), and hence I really really really hated Motoko (?), whose numbness and cowardice not only cost her two children and a huge area of forest (lol), but also caused the tragedy of the Yano family, which I still believe to be the most tragic of all incidents of the village

....
Ritsuko and Natsuno were probably the two characters who had the most honourable (?) deaths in the story...both stood by the human ideal that killing anyone with consciousness is wrong, and although both died as a result of standing by such ideal, they probably gained a lot of fans by doing so... Tooru, on the other hand, was really the most "human" person in a lot of senses...=w=;
Seishin and Toshio were probably two of the most important characters in the story....and they couldn't be more different on a lot of things...they were such a good couple (excuse me for the BLness lol) at the beginning, but value separated their paths...
Toshio: the realist, the experimental-scientist-doctor, leader of the human group at the end, doesn't care about his methods as long as he gets the results
Seishin: the idealist, the religious-yet-wondering-writer, companion of the surviving shiki (Sunako), doesn't mind the results as long as he follows his method...
I think a lot of people thought Toshio was cruel in his methods, but I thought it was the other way around...by allying with the shiki side, Seishin automatically denies that human lives and deaths are of equal weight --> One attack by a shiki can't kill a person, so to stop further killings, the fairest thing was probably to convince Sunako and the others to abandon the village, and hunt in the city to the extent that humans aren't killed....as hard as that would be... Sure, it's sad that Sunako can't be part of society, but is her "society" really more important than villagers' lives? In this sense I thought Seishin's actions didn't make any sense, and his ideology (and novel) was impossible to understand to me = = On top of that, he ended up killing someone directly and indirectly sacrificed his family and poor Mitsuo and his mom's lives. Where is the ideology in that? How is that not "cruel"? = =