Which anime do you enjoy with a mostly adult cast of characters?

Series

• Ghost in the Shell: Stand Alone Complex
• Black Lagoon
• Odd Taxi
• Moriarty the Patriot
• Cells at Work: Code Black
• Cowboy Bebop
• Trigun (1998)
• Psycho Pass
• Aggretsuko
• Panty & Stocking
• One Punch Man

Movies

• Patlabor
• Patlabor 2
• Ghost in the Shell (1995)
• Ghost in the Shell 2: Innocence
• Redline
• Porco Rosso
• Howl's Moving Castle
• Paprika
• Dead Leaves

Mushishi. Very serious, well-told stories told in single episodes. Occasionally a younger character will come along, but it's mostly adults, and the cast outside of the MC rotates episode to episode.

In no particular order these come to mind. Most of these are outside what I typically watch, but I did enjoy them.

Monster (Crime Drama) https://anilist.co/anime/19/Monster/

Mushishi (Psychological Slice of Life) https://anilist.co/anime/457/Mushishi/

One Punch Man (Comedy Action) https://anilist.co/anime/21087/One-Punch-Man/

TRIGUN (Action Adventure) https://anilist.co/anime/6/TRIGUN/

Hellsing (Vampire Action) https://anilist.co/anime/270/HELLSING/

Overlord (Evil Fantasy) https://anilist.co/anime/20832/Overlord/

I think a lot of the other answers here are being too generous with your rules and not giving you characters that both look older and are older.

I've completed quite a few:

• Violet Evergarden
• Vinland Saga
• Odd Taxi
• Cherry Magic!
• One Punch Man
• Saga of Tanya the Evil
• Delicious in Dungeon

Honorable mentions - depends on how strictly you'd define "mostly":

• Cautious Hero
• Frieren
• The Apothecary Diaries
• Spy x Family

Honorable mentions - unique circumstances:

• Cells at Work! - Your typical red blood cell lives for about 120 days :( The cells that look like adults do behave like adults though
• PLUTO - Robots' mental age can be different from their physical appearances

Ghost in the shell stand alone complex (and 2nd gig) was my first and still favourite anime.

My favorites have been :

• Bang Brave Bang Bravern - Big dumb gay robots
• Mobile Fighter G Gundam - Big dumb straight robots
• Redline - Just some fun racing action. Some of the best animation I've ever seen.
• Wotakoi - Love story between nerdy office workers
• Legend of the Galactic Heroes - The best space opera
• One Punch Man - depressed superhero

I loved Wotakoi. The 4 main characters are 26-28 and employed. It's in the especially rare category of adult romcoms. It's a shame the anime never got a second season, but the manga is finished so if you give it a watch and want to find out what happened after, give it a read!

Big O

Ninja Scroll

Read or Die

Samurai Champloo

Berserk (OG)

Blue Gender

New:

• Delicious in Dungeon
• Miss Kobayashi's Dragon Maid
• Odd Taxi
• Psycho-Pass

Old:

• Cowboy Bebop
• Black Lagoon
• Hellsing
• Vampire Hunter D
• Ghost in the Shell

Other:

• JoJo’s Bizarre Adventure - characters look way more adult than they are

Frieren - Beyond journeys end

A real fresh take on fantasy stories imo with a lot of themes I always wanted to be explored in the genre. In my last pen & paper group i played an elvish alchemist specializing in seemingly useless utility potion effects. And when i created the character i had a hard discussion with my dm on how elves actually pervice the world and other races, with them reaching ages of thousands of years and whatnot. And frieren adresses that perfectly. Also that soundtrack is just the best. I have yet to listen to "One last adventure" and not get at leas queazy, if not tearing up a bit.

Were currently watching it a second time, just a week after finishing first time. We've never done that with any series.

Highly recommended

Miss Kobayashi's Dragon Maid was pretty cozy, and features primarily adult characters.

A recent one I don’t see mentioned often: The Great Pretender

Loving all of the Odd Taxi mentions.

• Planetes (sofa king good)
• Hellsing
• Area 88
• Genshiken (adults but college setting)
• Read or Die
• Gundam 08th MS Team
• Excel Saga (the main cast are all adults, but it's a comedy and just about everyone is an idiot, so they won't necessarily act like adults)
• Gintama (main character is an adult, his sidekicks are not, but the majority of the cast is adult. Again, comedy, so maybe not "adult" enough lol)
• Cowboy Bebop
• Way of the Househusband
• Gundam Thunderbolt

From my spouse:

• Servant x Service

Not sure if it's considered true anime, but Castlevania on Netflix was excellent.

Genshiken
Bartender
Spice and Wolf
The Fable
Dungeon Meshi
Goblin Slayer
Saihate no Paladin
Shirobako
Psycho Pass
Wotakoi
Zom100
Golden Kamuy
My Home Hero
Kyokou Suiri
Vinland Saga - He's like 16 in the first half but grows up by the 2nd half.
Isekai Ojisan
Cyberpunk: Edgerunners
Blue Period
Megalo Box
Samurai Champloo
BNA
Aria
Ishuzoku Reviewers
NHK no Youkoso
Drifters
Trigun
Osomatsu-san

Odd Taxi (crime drama)

Psychopass (crime drama)

Cells at Work: Code Black (... Medical drama?)

Death Parade (Death game-ish)

Devilman Crybaby (main character is a high schooler, but it's irrelevant imo. I didn't remember until I looked it up again. This is a grim series )

Inuyashiki (Action. Old man is a complete Chad)

Panty & Stocking (Comedy)

Jellyfish Princess (Drama)

Saga of Tanya the Terrible (it's not really a kid, action)

Saint Young Men (Comedy)

Samurai Champloo (Action)

Shiki (Horror/Drama)

Monster (Mystery)

Rose of Versailles (Very old, but romance/drama)

Almost all of Satoshi Kon's work (including Paranoia Agent)

Ruroni Kenshin (Shounen)

Yurii on Ice (Romance/drama)

A few off the top of my head: Shirobako. Space Dandy. Samurai Champloo. Ghost in the Shell: SAC.

(trying not to duplicate other mentions)

Current:

• Ramen Akaneko - is a current show with working (adult) cats and a human running a ramen restaurant.
• The Fable - is a current show that I classify as Yakuza noir, about a uh... idiot savant assassin? I love Yoko.
• Kengan Ashura - Extremely violent bizarre macho underground fighters.

Recent:

• Paripi Koumei/Ya Boy Kongming - An absolutely fantastic blast about making it in the music industry. All of the music is sooooo good! All major protagonists work in a bar.
• Akiba Maid Sensou/Akiba Maid War - A parody of maid cafes operated like Yakuza gangs.
• Brave Bang Bravern - was a pretty good farce of 90s super robot shows with all adult military guys as protagonists.
• Glass Of God - was about godlike knowledge of bartending, so obviously no kids or teens there.

The recent film Blue Giant is great. About a young man who moves to Tokyo from rural Japan to pursue his love of jazz. Great visuals and music.

Call me a bit old fashioned, but Lupin III. Regardless of which part or movie, I tend to enjoy some of the sometimes wacky antics that occur.

Eureka Seven

if you want a fantasy story with emotionally intelligent characters, well-crafted themes and messages, great animation and music

this is a gift for you

This was harder to answer than I thought, pushing up to 20 eliminates a lot of contenders I think. I would say maybe Vinland Saga? The main character starts as a child, but it also covers a large time span so he hits twenty partway through the second season. Major recurring characters are almost all adults throughout. Its a semi-historical anime set mostly in England and Denmark during a war between the two. It's a show that deals heavily with violence and trauma, has some very complex characters, and I can't recommend it strongly enough

Wotakoi, Black Lagoon, Baccano (I think?), 91 Days, Akudama Drive, Golden Kamuy, Hakata Tonkotsu Ramens, ID: Invaded, Dragon Maid, Spice and Wolf, Wave Listen To Me! to name a couple

Shirobako

A Sign of Affection

Showa Genroku Rakugo Shinju

A lot of people already mentioned the ones I know of and mostly I only know of older shows that were geared to an older audience :/

Outlaw Star? Anything made by Satoshi Kon texhnolyze Megalo Box Baccano? Legend of The Galactic Heroes

Dungeon meshi is a recent one that comes to mind

I'd tentatively add Berserk to the list. Tentatively because the story does go back to recount the characters' youths, but that's really not the main focus.

Another good one with mostly adult cast and a more mature plot is Monster.

A few older series I haven't seen listed yet:

• Ergo Proxy
• Heat Guy J
• Pumpkin Scissors (note: has Unfinished Manga Syndrome, so the story stops without reaching a proper climax. Still fun.)
• Saiyuki (one of the four leads does look like a teen, so skip this one if that bothers you.)

Black Lagoon

The new Bartender anime was pretty good.

Golden Kamuy comes to mind.

The Great Passage and Showa Genroku Rakugo Shinju. The latter of which might start with them as kids but I feel like most of the show was with them being older.

Trigun

It's not an anime, per se, but the writing, voice acting and such are very much like an anime in the Like a Dragon series of games. Where it currently sits, all the characters are middle-aged or older. It also has a lot of existential dialogue and side stories that are extremely poignant, as someone who is also middle-aged in this time period.

The only actual anime I could even think of with main characters my age or older that I also enjoy is Cowboy Bebop; and that's about 50-50 because of Faye and Edward. I've seen some episodes of Bartender but I wouldn't go so far as to say I enjoy it yet. It's a bit dry.

Vinland saga

Lots of good stuff in this thread already, will suggest Black Magic M-66 and Megalobox.

"The Saint's Magic Power is Omnipotent" was pretty good. I agree with lots of the others people already listed, but this one makes her age a relevant plot issue which basically sets the tone. It's a romance anime with light combat and a good amount of world building. 2 seasons.

What you want is "seinen" anime, which is intended for an older audience. Most anime is "shonen", which is intended for kids. (Not that there's anything wrong with an adult enjoying shonen.) There are more genres and specifications, but I am not that into anime.

Dragonball is shonen. Cowboy Bebop is seinen. There are loads of great seinen shows out there.

Heh, does western anime count?

Legend of Korra, Vox Machina, DOTA: Dragons Blood

And Pantheon.

For heaven's sake, if you have not watched Pantheon, correct that immediately. Techically the cast is young, at first, but it doesn't feel like that at all.

"Spice and Wolf". It's a great story with adult characters. MC is like 26 years old and the themes in this show are also for mature audience. There is a series from 2008 but they also made a remake that is currently airing. As a fan of original series I'm enjoying it very much.

Do 1000+ year old characters that look young count?

I mean, I don't remember watching an anime that has a character like that, but IDK some people are really weird about that.

Fullmetal Alchemist (both of them). The two main characters are basically the only teenagers, and only one of them looks it.