Thank you for your answer.
However, I don't find the furigana in the pdfs transcription of the lessons, there is a romanization and hiragana translation, which is not the best option, let me explain myself. The furigana is different from the romaji or kana transcription, the furigana system is the hiragana trasncription in the upper side of the kanjis, it allows you to read the kanji, and at the same time, still looking at the kanji iself. With the actual system, when I am reading the transcription and I don't know one particular kanji, I have to break up my reading and look for the romaji or the hiragana transcription in other part of the document or section. Also, If there are a word composed for two or more kanjis, the romaji or kana transcription doesn't make clear what part of the trasnsption correspond in the word with the kanjis individually. Therefore it is a little bit annoying. The furigana solution, is in my opinion, the optimal solution.
Again, thank for your interest