As for the main meaning of the “Medicine King Bodhisattva” chapter, it is in the seventh fascicle of the sūtra and is the 23rd of the 28 chapters. The first fascicle of the Lotus Sūtra includes the “Introductory” and “Expedients” chapters, the former being the introduction to the 28 chapters. The eight chapters from the “Expedients” to the “Assurance of Future Buddhahood of Learners and Adepts” chapters chiefly clarifies the attainment of Buddhahood by the Two Vehicles of śrāvaka and Pratyekabuddha and secondly explains the attainment of Buddhahood by bodhisattvas and ordinary people.
The five chapters, “The Teacher of the Dharma,” “The Appearance of the Stupa of Treasures,” “Devadatta,” “Encouragement for Upholding This Sūtra,” and “Peaceful Practices” chapters, expound the way ordinary people in the Latter Age of Degeneration should practice the eight chapters following the second “Expedients” chapter. Also, the 15th “Appearance of Bodhisattvas from Underground” chapter is the introductory to the 16th “Life Span of the Buddha” chapter. The 12 chapters beginning with the 17th chapter, “Variety of Merits,” explain mainly how ordinary people in the Latter Age of Degeneration should practice the “Life Span of the Buddha” chapter, while in the second place they also preach how to practice the eight chapters beginning with the “Expedients” chapter. Accordingly, this “Medicine King Bodhisattva” chapter explains the way to practice the eight chapters following the “Expedients” chapter as well as the “Life Span of the Buddha” chapter.
Yakuō-bon Tokui-shō, The Essence of the “Medicine King Bodhisattva” Chapter, Writings of Nichiren Shōnin, Faith and Practice, Volume 4, Page 27-28