To attend mantra siddhi(realising the deity), one has to do purasharana(x japa, x/10 homa, x/100 tarpana, x/1000 marjana, x/10000 bhojanam).
Even in many references they are saying about anusthana, which is looking similar.
Questions:
Are purascharana and anusthana same?
Naam japa can have purascharana/anusthna ?
Reference:
