Tobira Gateway to Advanced Japanese Learning through Content and Multimedia assumes 297 kanji are already learned by its potential readers. Tobira presents many words using these kanji without furigana. Learning the statistically most common kanji on- and kun-readings through WaniKani makes Tobira more accessible.
The following table shows what percentage of these prerequisite kanji are covered at particular WaniKani levels:
Level 5: 40%
Level 10: 76%
Level 15: 92%
Level 20: 97%
Only nine prerequisite kanji are introduced by WaniKani after level 20: 職違質授痛貸婚汚遅. The other 277 required kanji are covered in the first 20 levels.
The following snippet, with furigana as provided in Tobira, is extracted from page 5 of the textbook：
首都）、一道は北海道、二府は 大阪府と京都府で、その 他は、 静岡県や 広島県のように全部、県です。静岡県はお茶や 富士山で有名で、広島県には 戦争の 恐ろしさと平和の大切さを伝える 原爆ドームがあります。
Working through level 20 on WaniKani will not give language students the ability to know all vocabulary in the above text. However, they will be able to make good guesses at how to read words such as 都道府県 and use online dictionaries like Jisho. Several words with furigana included by Tobira, such as 他, 大阪, 広島, and 戦争, should be known by WaniKani users at level 20. If Tobira is a gateway to advanced Japanese, then WaniKani is a great tool to develop vocabulary and reading skills needed to pass through that gateway.