What you learn, and when 手習い
Kana first, then a handful a day. The two kanji orders, why one is the default, and why switching costs nothing.
The hardest question a learning app has to answer is not what to teach. It is how much to hand over at once. Give somebody two thousand characters on day one and they will study none of them.
Kana first
You start with 10 hiragana and 10 katakana. Kana is the writing system underneath the writing system - every kanji reading is written in it, so learning it first means every later reading is something you can actually read rather than a shape you are copying.
It also pays off within a week, which matters more than it sounds. Furigana, the small kana printed above a kanji, becomes legible almost immediately, and from then on it is drilling itself every time you look at the screen.
If you already read kana, say so at signup and take the 関所 checkpoint placement sprint instead. It verifies kana rather than assuming it - all 220 open at once, rather than ten a day.
The sprint is rapid-fire and one try per card. Everything you clear seeds straight into your rank, so a genuine veteran finishes in about ten minutes and starts around level 4 or 5. Anything you miss simply joins your study queue - nothing is lost but the bluff.
Kanji wait until the checkpoint is behind you, the same way they wait for everyone else. The difference is how long that takes: clear the queue and your first 6 kanji are there to unlock the same afternoon, where the slow road reaches them in three weeks. Miss half the kana and it takes longer - which is the checkpoint doing its job, not a punishment. Nothing you have unlocked is ever taken back.
A handful a day
After that, new material arrives once a day: 5 hiragana and 5 katakana, or 3 kanji - and only once the queue in front of you is clear. The day turns at midnight in your own zone, set on your account page.
A plan opens that same door a second time each day, and the second turn waits on a clear queue exactly as the first one does. The handful is the same size either way, so a day on a plan is 10 kana sounds or 6 kanji, arriving as two batches rather than one. It is the only thing money makes faster here, which is why it is written on the plan page rather than left to be noticed.
The condition is the important half. Unlocking on a timer produces a backlog nobody asked for; unlocking only when you are caught up means the pile in front of you is always one you built. It is a slower ramp than most apps offer and it is the reason the ramp survives.
Two orders to learn kanji in
School order is the default. Characters arrive after the pieces they are made of, so a new kanji is usually a recombination of ones you already know - the writing system taught as a system rather than as a list.
Exam order follows the JLPT levels, N5 through N1. It exists for people with a test date, who need coverage of a published list rather than a sequence that builds.
The two disagree a great deal (校 is a first-grade character and also N4), so switching mid-journey does mean meeting a batch the other order had skipped. That is correct, not a fault. And switching costs nothing: unlocked characters are never taken back, so a change only affects what arrives tomorrow.
How words arrive
A word opens when you know what it is spelled from. 一つ appears once 一 is yours; 大使館 embassy waits for all three of its characters. A word with no kanji in it follows the same rule on its own terms: それ waits for そ and れ, and waits for them in the script it is written in - katakana study is what opens a katakana word. A word built of characters you cannot read is not a vocabulary item, it is a guess.
Words are handed over ten a day, through the same unlock as everything else. Mastering one common kanji can make forty words eligible in an afternoon, and a queue nobody asked for is a poor reward for studying well. Whatever is earned and waiting is shown on your dashboard, the most useful words come first, and nothing in that pool is ever lost or expires.
Each word is asked as a translation, and as kana writing where the writing is the thing worth knowing. Its example sentence is shown as context, with the word itself hidden behind 〜 until you have answered - so the sentence helps you place the word without handing it to you.
Nothing is gated by level
Your order is a preference, not a permission. No character is locked behind a rank, a level, a streak or a payment. What you know is the only thing that gates anything at all, and the only thing it gates is the vocabulary above - which is paced, never withheld.