Bartender is actually a manga series by Araki Joh, and the artwork is by Nagatomo Kenji. This series finished a few years ago with 21 volumes. However, it's not licensed in English. You can still somehow find the English translation. Anyway, I have not finished this series yet, but I adore it with all my heart. The artwork isn't extravagant, but I feel like it's a good thing it isn't. Every single chapter has a message about how to treat others with kindness and respect and how to keep your life going; each one of those messages is expressed through the history of cocktails and liquor, references to famous writers and artists, and a customer's troubles. In addition, none of these messages are told in cliche ways such as, "Life is like a roller coaster." Joh always uses a unique metaphor or simile for such popular meanings so readers can view them in different perspectives without rolling their eyes and saying, "Yeah, I already know that." Also, there's an anime adaption to it, but it only has 11 episodes. This itself is very unique and beautiful, though. The art style is a bit different from the manga, but the animation style is kind of like a play because of the narration scenes, and each episode has relaxing jazz music. And personally, jazz music makes almost everything better.
If you do decide to read the series, I suggest listening to all the soundtracks, including the opening and ending songs. I guarantee you that they will make reading much better. The first two songs are in Japanese, but even if you don't understand the language, I still highly suggest you to listen to them. If you're the type who absolutely needs to understand the language, then you can search the translations up.
Soundtracks:
Bartender - Natural High ft. Junpei Shiina
Hajimari no Hito - Natural High
[By Ootake Kaoruko]:
NO NAME ~Kami no Glass~
GRASSHOPPER ~Taiketsu~
COSMOPOLITAN ~Iropposa~
MARTINE ~Seiren Sareta Mono~
HIGHBALL ~Kitsui Seikaku~
MARGARITA ~Ningyou no Ie~
MOURIN ROUGE ~Ginza no Machi~
BLUEMOON ~Kanashige~
MANHATTAN ~Utsukushisa~
SIDECAR ~Kiyowa~
SONORA ~Rekishi~
RED EYE ~Omoomoshii~
BLOODY CAESER ~Kenka~
NIKOLASCHIKA ~Fukai~
B&B ~Ochikomi~
GODMOTHER ~Suneru~
ROB ROY ~Jukusei~
MILLION DOLLAR ~Kangeki~
HEMMINGWAY'S DAIQUIRI ~Roujin to Umi~
KIR ROYAL ~Kanashimi~
GIMLET ~Taiji~
GIN TONIC ~Oyaji~
CINDERELLA ~Kitaikan~
RASTY NAIL ~Ningenmi~
AMARETTO ALEXANDER ~Youki~
BLACK VELVET ~Comical~
PARADISE ~Nichijou~
MOSCOW MULE ~Yasashisa~
OLD PAL ~Aishuu~
CHRISTMAS CHAMPAGNE ~Kiyoshikono Yoru~
BARTENDER ~ Bartender~ (piano session KW011)
Hajimari no Hito (piano session KW010)
Bartender - Natural High ft. Junpei Shiina
Hajimari no Hito - Natural High
[By Ootake Kaoruko]:
NO NAME ~Kami no Glass~
GRASSHOPPER ~Taiketsu~
COSMOPOLITAN ~Iropposa~
MARTINE ~Seiren Sareta Mono~
HIGHBALL ~Kitsui Seikaku~
MARGARITA ~Ningyou no Ie~
MOURIN ROUGE ~Ginza no Machi~
BLUEMOON ~Kanashige~
MANHATTAN ~Utsukushisa~
SIDECAR ~Kiyowa~
SONORA ~Rekishi~
RED EYE ~Omoomoshii~
BLOODY CAESER ~Kenka~
NIKOLASCHIKA ~Fukai~
B&B ~Ochikomi~
GODMOTHER ~Suneru~
ROB ROY ~Jukusei~
MILLION DOLLAR ~Kangeki~
HEMMINGWAY'S DAIQUIRI ~Roujin to Umi~
KIR ROYAL ~Kanashimi~
GIMLET ~Taiji~
GIN TONIC ~Oyaji~
CINDERELLA ~Kitaikan~
RASTY NAIL ~Ningenmi~
AMARETTO ALEXANDER ~Youki~
BLACK VELVET ~Comical~
PARADISE ~Nichijou~
MOSCOW MULE ~Yasashisa~
OLD PAL ~Aishuu~
CHRISTMAS CHAMPAGNE ~Kiyoshikono Yoru~
BARTENDER ~ Bartender~ (piano session KW011)
Hajimari no Hito (piano session KW010)