Dr. Hana is weird. She pays attention to celebrations and other people's birthdays, yet she doesn't really care about her own...

SilverAsh
After wrecking his brain, in their peaceful days in Victoria, Enciodas gave her an antique-looking box, saying that he'll give her something new to put in every year. Alas, he couldn't give anything to her for a few years when she went missing. Would be great if he gives her a ring someday. [Yes, this is totally from Persona 3 Portable, I just love this idea so much okay]
Since Hana's birthday is only one day apart from Encia, she likes to remind him to give something to Encia too if possible.

Cliffheart
Their birthdays are only a day apart, so they celebrate both at the same time. They either cook for each other or go out to have lunch and shop together. Girls-only party

ABC trio (Aosta, Broca, and Chiave)
Aosta and Broca think of making something like their tokens, but Chiave combines it: a miniature landscape with a handmade doll of Dr. Hana. Plus a more intricate badge with her name on it.

Executor
He has zero idea on what to give. After wrecking his brain and asking people around him, he ends up just making various desserts for her. But he makes too many, so they're shared to everyone available.

Blue Poison
She bakes a cake that looks more like a wedding cake. Probably cook with Executor, helping each other out. Everyone's going to die of diabetes at this rate.

Adnachiel
He also makes sweets with Executor's and Blue Poison's help. Everyone's totally going to die of diabetes.

Gravel
"I'm your present, Doctor"
The rest is redacted.

Flamebringer
After being nagged by the Gardening Club, he makes a banquet of flowers and throws it on her face.

Flint
Not wanting to lose to Flamebringer, she makes a flower wreath and gleefully puts it on Dr. Hana's head.

Perfumer
She gives a new, antique-looking vase with beautiful flowers and puts it in Dr. Hana's office. She also takes care of it whenever she can.

Mostima
Let's just say they have a romantic night together.

Leonhardt and Ayerscarpe
Leonhardt takes her to a trendy shop and buys her cool-looking clothes and/or shoes. Ayerscarpe tags along and later on gives her a box full of edamame.

Thorns and Elysium
At first, Thorns doesn't really care and intends to just give her a mysterious potion, but Elysium nags him and drags him into some sort of competition. They end up dressing up well and have a date with her, where they're the one paying for everything. Yes, the 3 of them together.

Phantom
He has zero idea on what to give, part 2. [I think I better wait for translations for Rewinding Breeze event for better understanding of him before I can write about him. He appeared there, right I can't find any translations so far, only the one with Elysium. So for now, all I can think of is:]
Phantom: "Doctor, is birthday important to you"
Dr. Hana: "If it's my own birthday, not really. What about it"
Phantom: "...I don't know what to give for your birthday tomorrow."
Dr. Hana: "It's fine to not give anything. Saying "happy birthday" is enough. As long as your feelings reach me, it's enough."
Phantom: "..." (has a complex expression on his face)
Phantom: "...If there's anything you want, I want to hear about it."
Dr. Hana: "..." *suddenly grabs him close*
Dr. Hana: "What if I say I want you to kill me Will you grant it, then ...Just kidding."
[...Wait, that's a bit too much I'll cut it here, but you get the gist. They just have some talk and spend some time together. That better be a fanfic for next time lmao.]