So I'd like to watch more Jdrama, but don't know what to watch. I feel like a dummy because I'm part Japanese yet I've only seen about three Jdramas and I'd also like to talk to my grandma about all the actors and stuff because she seems like she wants me to like it too?? So I'd like to start with the really popular ones, if you guys could suggest any. Like if I was talking about Korean ones (I'm trying to make this make sense, please bare with me), what would be the Descendants of the Sun of Japan? What are the must-watch Japanese dramas that will help me enter the Japanese drama fandom?
I don't believe I'm qualified to give recs for Jdrama, since I have myself seen very few, but these are a few ones that seemed pretty popular-
A Girl & 3 Sweethearts
Please Love The Useless Me
We Married As A Job
Tatta Hitotsu no Koi
And if you're interested in the classics, there's always- Hana Yori Dango & Itazura Na Kiss
Hope it helps!
Hi, as far as I know, prime-time drama ratings in Japan have sunk even lower than in South Korea these days. To get something that was really a big mainstream phenomenon (if any), I think you need to go back to the '90s. Tokyo Love Story, any drama that Takuya Kimura did in the '90s--I'm sure people more knowledgeable than me will give some recs.

If you're talking about new dramas, however, I'd second what @AnanyaS had recommended: We Married as a Job, which was really a major success and as close as a Japanese DotS that I can think of. Oh, and it even sparked a cultural phenomenon called the "Koi Dance" (look it up).

And since you mentioned about your grandmother and how you wanted to have something to talk about with her, what about trying some asadora? They're morning daily dramas, about 15-minute per episode. (Quite popular among women, and traditionally almost always enjoy high ratings.) The episode count is rather intimidating--but hey, they're short, and since they're made so that homemakers can watch them while doing chores, you can skip and fast-forward if some parts felt boring, without losing the gist of the story.
All time favorite, must watch: Hana Yori Dango

Depending in your interests:

ROMANCE

Buzzer Beat
Love Shuffle
Pride
Tatta Hitotsu no koi
Hotaru no Hikari

DRAMA
1 litre of tears
Byakuyako
Koizora
Taiyou no kisetsu
Soredemo, ikite yuku
Sekai no Chuushin de, Ai wo sakebu

COMEDY
Atashinchi no Danshi
Hanazakari no Kimitachi e
Ouran High school host club
Mei-chan no shitsuji
My Boss, my hero

SLICE OF LIFE
Nodame Cantabile
Rookies
My girl
GTO
Gokusen
Dragon Zakura

SUSPENSE ( japanese suspense dramas are very good, do try them, this dramas are 10, 9 and 9.5 for me)
Maou
The quiz show 2
N no tame ni
Ryusei no Kizuna
Liar Game
Kazoku game
Kurosagi

SPORTS
H2

MOVIES
Death Note
Rurouni Kenshin
Bokura ga ita
Heroine Disqualified
Paradise Kiss

Hope this helps you :D
Thanks for the recommendations! I'll make sure to check them all out!
I agree with most of the recommendations already given! I most definitely second (and third, and fourth) Nigeru wa Haji da ga Yaku ni Tatsu, and I'll also add a couple of early-mid 2000s recs:

Tiger & Dragon (comedy) -- I found this hilarious, plus it focuses on rakugo which might be fun to share with your grandmother, if she would like you to know more about traditional Japanese entertainment~ (this is unrelated but I finally saw my first rakugo performance IRL this month--it was SO GOOD! if you haven't seen one already, I recommend it!)

One Million Stars Falling from the Sky (mystery, thriller, romance, tragedy) -- starts off a little slow but IMO it's worth a watch (and a rewatch ;D)
Anything with Kimura Takuya as the lead role except A Million Stars Falling From The Sky. Sorry to the person who posted above mine, it was a multi-awarded series but it felt dragging for me. I would recommend BEAUTIFUL LIFE - though it's heartbreakingly beautiful, CHANGE and GOOD LUCK!!.