Budget for four separate things, and get each one in writing: the language course in Nepal, the consultancy service fee, the government NOC, and the costs in Japan itself.
The No Objection Certificate is NPR 2,000, paid to the Ministry of Education. A Japanese language course in Kathmandu is a separate charge from any consultancy service fee, and the two are frequently quoted together in a way that makes comparison hard. Ask for them separately. The reported range for consultancy service fees generally is roughly NPR 15,000 to 45,000, from a single secondary source.
Japanese language schools charge tuition, and most require a deposit and evidence of funds before issuing the documents you need for a visa. Living costs vary sharply between Tokyo and regional cities. Ask your provider for the specific school’s published fee schedule rather than an estimate, and check that the school exists and is accepting students.
Ask what happens to each payment if the visa is refused. Refusal rates change, providers are now liable to compensate students left stranded or placed with fraudulent institutions, and a written refund position before you pay is worth more than reassurance afterwards.
Budget separately for the language course in Nepal, the consultancy service fee, the NPR 2,000 government NOC, and the Japanese school’s own tuition and deposit. Ask for each in writing.
NPR 2,000, paid to the Ministry of Education, issued in three to seven working days.