Where in one of their friend/comrade/teammate/nakama/etc dies or sacrifice themselves? 🙂

Preferably completed and lengthy ones 🙂

Akame ga kill!, incomplete though. Maybe Berserk but it's incomplete as well.

Both Basara and 7 Seeds have tragic moments (they are by the same mangaka). I haven't finished Basara, and 7 Seeds is ongoing, so I don't know if they will end with redemption, but so far 😢 😢 😢

Angel Sanctuary, and also YUKI Kaori's Godchild
Hunter x Hunter, also ongoing, is exactly this. Little

in the Phantom Troop arc, on the villains side

Threads of Time - I've only read the first volume, but it's shaping up to go there.

Rave... its more towards the end.. T^T gosh I dont want to spoil anything...

Hoshi no Samidare

Second Basara and 7 seeds.
Also,
seinen:
Shin Angyo Onshi

shounen:
D. Gray Man
Pandora Hearts
Nabari no Ou

shoujo:
+C: Sword and Cornett
Cantarella
God Child
Reimei no Arcana

Rave Master
Hatenkou Yuugi... er, it's incomplete, but it is long. Despite tags it's really not much romance, just friends/family.

WEBTOONS ヽ( ★ω★)ノ

I can't really remember if anyone dies in these:
Sora wa Akai Kawa no Hotori
Saver
Tokyo Crazy Paradise
Kanata Kara

Owner of Antisense Scanslation.

07 Ghost is good one for what your looking for, pretty sad though
RustBlaster too, though if i remember correctly he ends up not being dead in the end

[img]http://24.media.tumblr.com/3b280fafb72cad0f718be64368e64ca7/tumblr_myylzmuiY41rw3pzao4_250.gif[/img]
Like educational manga? take a look at Ed U. Manga's list of manga here

Thank you for your recommendations!!!