Systems Atlas Project
Shutoku 習得
Free on the App Store · iPhone, iPad, MacReviewed just before you would have forgotten it.
Retention decays on a schedule you cannot feel from the inside, so it has to be scheduled from outside. Shutoku picks the moment for you.
Not derived from the map · built from a gap noticed directly
How it schedules
The interval is the whole product.
A review that comes too early wastes the repetition; too late is relearning. Shutoku tracks how securely you know each word and places the next sighting at the point where recall is about to fail.
Words you hold well recede. Words you keep losing come back sooner. There is nothing to tune.
Spaced repetition
The scheduler works from your own answer history for each individual word, not from a fixed ladder of intervals applied to everything.
Verb conjugation
A full conjugation engine covering て-form, た-form, negative, potential, causative and passive. Any verb can be drilled in any of its forms.
Dictionary
Vocabulary across JLPT N5 to N1, searchable by reading, meaning or level. Reviews can be filtered to the band you are sitting.
Kana and romaji
Hiragana, katakana and romaji, switchable at any point. Romaji is a ramp, not a destination.
Progress
Daily review counts, retention rate, and vocabulary growth over time. Enough to tell whether the schedule is working.
Sync
Shutoku requires a free account — an email address and a password. It is what carries your vocabulary, progress and review schedule between your devices, and it is set up the first time you open the app.
On the name
習得
Shutoku — to acquire through study and practice. To make something yours rather than to hold it temporarily. The scheduler exists to move words across that line.