To pronounce correctly "L" and "R" of English I misunderstood. I was arrogant. I've been thinking myself I have no problem with English pronunciation. None of my English teachers pointed out my pronunciation in my school days. So, when I mixed up the "L" and "R", we did not have any trouble to communicate. I became thinking that it is not a big problem to mix up "L" and "R". But, thanks to my tutor and teacher from Italki, I realized my thinking was a huge mistake. I dealt with the pronunciation training lightly. When I think about it, my school days teachers were very trained to Japanese students' pronunciation. And they were accustomed to presume meaning from contexts. Now I got many tips from my teacher to train myself to pronounce "R" sounds correctly. I tell myself to practice out loud at least 10 times a day!