What should I need to learn first to understand Japanese?

First of all I am telling you, it's all my personal thoughts not any researched topics. Basically I think we need to understand first Japanese characters to understand Japanese and the learning journey.

But the reality is when we were small baby's what we learn first characters or speaking?

Correct! We learn first how to talk by speaking and listening our family members right! But you have already passed that away, now we are busy with our daily life and we don't have enough free memory or time to spend hours of time to practice with mistakes. We are more capable and matured than the old days.

We are able to read by ourselves and watching TV series, movies or youtube videos of related learning resources, so if we understand the characters we will be able to recognise and do continuous practice regularly.

Now let me tell you, there are three different characters in Japanese language system. In my mother language it's only two, I am speaking about Bengali.

They are :

  1. Kanji
  2. Hiragana
  3. Katakana
In addition to these, Japanese also use Roma-ji (a,b,c) and numerals (1,2,3).

1. Kanji : Kanji were bought over from China around the time of the 4th century.

Kanji Characters

2. Hiragana : Hiragana was created from Kanji, Hiragana are simplified forms of kanji. Hiragana are mainly used to write function words such as native Japanese words or particles.

Hiragana Characters

Hiragana simplified forms Kanji

3. Katakana : Each Katakana was formed by taking one part of a Kanji. Katakana are used mainly to write foreign loanwords.

Katakana Characters

Katakana formed Kanji

Note : Hiragana and Katakana, 1 character express one syllable. The character itself has no meaning. 

My suggestions is to memorise Hiragana and Katakana first and then try to memorise Kanji.