Nichiren’s view on Maitreya

Nichiren viewed Maitreya as “one of the protective forces” and a function of “guarding and helping” the Bodhisattvas of the Earth:

“Moreover… all the bodhisattvas, Bodhisattva Maitreya … will guard and protect the
votaries of the Lotus Sutra,  so one may indeed rest assured”. WND1 p1074

In his writing, Nichiren mentions the traditional Buddhist views on Maitreya - however, he clearly explains that the future propagation of the Eternal Dharma of the Lotus Sutra was entrusted by Shakyamuni - not to Maitreya, but - to the “Bodhisattvas” of the Earth :

“The Buddha did not entrust these five characters to Maitreya, Medicine King,
or the others of their group. Instead he summoned forth the bodhisattvas….                               
from the great earth of Tranquil Light and transferred the five characters to them”. WND1 p437

In view of Nichiren Buddhism, each person embodies the character of “the Maitreya” because Maitreya is a metaphor for the function of compassion :

“The name Maitreya means ‘Compassionate One’
and designates the Votaries of the Lotus Sutra” Orally Transmitted Teachings p 143.
Expecting Maitreya: A myth based on disbelief in the potential of humanity

The mythology of Maitreya (as the “second in line” Buddha) implies that no one in the history of humanity was able to become a Buddha equal to Shakyamuni, and no one will – until the emergence of a “new” Buddha Maitreya. 

This myth makes Shakyamuni Buddha a “failed teacher” who could not convey a teaching which would raise others to his level of Buddhahood. 

Additionally, such concepts of Traditional Buddhism convey also a disbelief and doubt in the potentials of human beings and their capacity to reveal Buddhahood.  The idea of a saviour “descending from Heaven” contains a sense of inferiority of ordinary people, as being themselves incapable of embodying - in the depth of their lives - the Universal Dharma and the capacity to transform their life.