Greetings and salutations... ok enough of that. This is a short yet large guide detailing...
1. How to route
2. How to achievement
In Oblivious Garden. The achievements are stuck in a design I devised with awkward in mind, when in doubt CTR+F is your friend. Also, the routes have been laid out in such a fashion to put strain on your eyes, remember to thank me in the comment section for you now buff eyes.

These achievements are simple to obtain, and considering how self-explanatory they are, I won’t bother going into much detail. After obtaining the starter ingredients from a play though, you can access Finn’s teatime under the memory menu and simply brew all the teas.

Make D rank tea for the first time.


Make S rank tea for the first time.


You made the most tasteful tea.


Collect all tea ingredients.


Collect all the tea recipes.


Get S rank in all kinds of tea.


Get the highest level in tea game.


In the event you are still having trouble, simply follow the tea recipe guide linked below. By the time you have made all of the tea's, you will have the above achievements.
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=355208159

Meet a strange lady in a strange place.

• During your first encounter with Dyanna, choose "Yes, i did."

All you have to do is to be a good listener.

• Follow Dyanna to the library and listen to her story.

That is not a documentary fiction, my princess.

• During the scene Fencing Class Incident, choose "Instruct Dyanna."

The princess and the prince promised to be together forever.

• During the scene Rose and Nestling 3, choose "Say something to ease the situation."

You fail to satisfy the princess, dont you?

• During the Delicious Soup scene, choose "The one on the right."

From now on, you live happily ever after.

• Complete the good ending on Dyanna's route.

Dyanna - Tea Party (First Meet - Dyanna)

• Yes, I Did

Meeting Incident -- Finn

• Talk about gardening

*Dinner Party*

Dyanna - Hanging Roseland (Rose and Nestling)

• Sit distantly

Dyanna - Main Hall (Good Child’s Myth Class)

• Go together
  
• Stay and look for the book by myself

Fencing Class Incident

• Instruct Dyanna
  
• Because you trust me

After the Fencing Class - Dyanna

• It was someone from the outside?

Dyanna - Hanging Roseland (Rose and Nestlings Part 2)

• Talk with Dyanna for a while

Dyanna - Main Hall (Teatime in the Afternoon)

• Compliment her

Dyanna - Main Hall (Residual Sound of the Dusk)

• She wants to reach the sun?

Dyanna - Hanging Roseland (Rose and Nestling 3)

• Say something to ease the situation

Dyanna - Main Hall (Delicious Soup)

• The one on the left

Dyanna - Main Hall (Past and Present)

• Just leave

Dyanna - Hanging Roseland (Nestling, alone)

• Of course you have my word

Dyanna - Library (Nicolas Playing Hide’n’Seek)

• Help her search

Dyanna - Main Hall (Before the Miracle Play)

• Check her condition before leaving

It is not polite to peep at a lady's diary.

• During your first encounter with Leira, choose "Leave the notebook alone."

Enjoy Leira's violin playing.

• During the scene Mysterious Melody, choose "Step Forward."

The tea you made is not good enough to win the princess.

• This one is probably the least straight forward achievement, for this you have to make Rank A tea during the competition between Dyanna and Irell, in the scene Twin Roses (2).

Do not tell this secret to anyone.

• Obtained during the scene Something to Fear by choosing "More like I enjoy this kind of life."

Come across Marian at the fencing hall.

• You stumble upon Marian on Leira's route, just follow her route and you'll get this.

A lily would be nice.

• During the Celebration scene give the lady her lily.

I may, or I may not, who knows?

• During the scene Leira - 5, choose "I may, or I may not, who knows?"

This is an unexpected ending.

• During the scene Leira - 6, choose "There is nothing I can do for you."

It is destined that we meet each other again.

• Complete the good ending of Leira's route.

Who is that girl? You will never know.

• Complete the bad ending of Leira's route.

This route is just like the others, stalk the girl everywhere she goes, and choose the least offensive choice. Also there will be a total of four Finn’s Teatime mini-games throughout the play through. I hope you studied your tea!

Leira - Tea Party (First Meet - Leira)

• Open the notebook, determine the owner

Meeting Incident -- Finn

• Talk about writing

*Dinner Party*

Leira - Tea Party (Mysterious Melody)

• Step Forward
  
• Give a compliment

Leira - Main Hall (Twin Roses)

• Try to calm Leria down

Leira - Main Hall (Fencing Class Incident)

• Pursue Leira to practice

Leira Incident after Fencing Hall

• Have you ever dreamed of a peaceful life?

Leira - Tea Party (Tea Art of the Princess)

• Leave anyway

Leira - Hanging Roseland (Unexpected Meet by the Lake)

• Please give me your order

Leira - Maple Woods (Something to Fear)

• More like I enjoy this kind of life

*Twin Roses(2)*

Leira - Maple Woods (Azure Desert)

• Keep Silent

Leira - Festival Incident 2

• Don't you like the festival tomorrow?
  
• Maybe you want to see the world outside?

Celebration

• White lilies

Leira - 1

• I have no idea

Leira - 2

• Maybe I should apologize to her

Leira - 4

• You are right, but that is not my way

Leira - 5

• I will not change my mind

Leira - 6

• Yes I Will
  
• Knock the door softly (Good End)
  
• Leave the room quietly (Bad End)

Sigh, that ending though...

Some things are better left unsaid.

• During the scene Meeting Incident -- Finn, choose "Talk about fencing."

Something serious may happen if you were not quick enough.

• During the scene Fencing Class Incident, choose "Watch Lin and Charlotte practice."

Are there any secrets behind her?

• Play route -> get achievement.

Here comes emperor of Celantu.

• Simply play through Lin's route, you will unlock this during the scene Broken Sword.

Lin accomplished her dream, and so did you.

• Simply play through Lin's route, you will unlock this during the scene White Night.

For some reason the game sees it fit to call Lin by her last name of Zhanning during the map segments. It’s too long, just call her Lin like everyone else.

Dyanna - Hanging Roseland (First Meet - Dyanna)

• I suppose so?

Leira - Tea Party (First Meet - Leira)

• Leave the notebook alone

Meeting Incident -- Finn

• Talk about fencing

*Dinner Party*

Fencing Class Incident

• Watch Lin and Charlotte practice

Dyanna - Main Hall (Teatime in the Afternoon)

• Let her taste by herself

Not many choices like Finn's path, but unlike Finn's path you still have a long way to go~

You go your separate ways.

• Complete Finn's route.

First Meet - Dyanna

• I suppose so?

First Meet - Leira

• Leave the notebook alone

Meeting Incident -- Finn

• Talk about fencing

Dinner Party

• The curious princess dressed in blue
  
• The elegant princess dressed in lavender
  
• The quiet eastern princess
  
• I want to know the young maid as well...

Finn (Tea Party)


That's it, once you join Finn for a tea party you are stuck on her route and will have no more choices through its resolution.

These are the miscellaneous achievements that didn’t go along with any specific character route. They have mostly to do with quick and simple tasks such as sleeping through the credits and pretending to care about what the voice actors think of their roles.


Watch the credits.

• Watch the credits by going to the main menu and selecting memory > credits.

Read all epilogues.

• Read all the epilogues; you must complete a character's route in order to unlock their epilogue. You can find the epilogues by going to the main menu and selecting memory > memory.

Unfortunately, you didn't finish your job.

• Get a bad end, you can find a bad ending by simply choosing not to stalk one specific character around and instead diversifying your portfolio, or by following a character's route and diverging on the final choice.

You finished your job, but this is not the end of the story.

• Complete all the character routes.

Finally lose the friendship with Rumi.

• Complete the scene Prologue.

It's you and not the others.

• During the second choice choose "Don't stop her."

Leave the fencing hall.

• During the scene Die Plebeian! choose "I can't die like this..."

Make tea that is fit for a princess.

• During the scene Die Plebeian! choose "Beat her first."

Finish the special chapter.

• Go under Memory > White Day and complete any route.

And that’s it for this guide, hope you found it useful. This kind of game doesn’t really need a walkthrough guide considering how easy it is to brute force through, as well as the awesome return system, however that’s no excuse not to have one anyways!

Seriously though, every visual novel needs that return button, it's epic.