I think the advice from bamboozled is great.

Japanese can also just appear very strange. To make sense of the grammar, I would advise maybe checking some of the youtube videos by cure dolly. She explains grammar really well - not from a scholarly point of view, but from a more human point of view. i.e. "why is the grammar like this" rather than just explaining "this is how it works".

https://www.youtube.com/playlist?list=PLg9uYxuZf8x_A-vcqqyOFZu06WlhnypWj

Hi, I don't really know Japanese but I've been struggling with listening comprehension in Chinese for quite some time.

Here is a technique that helped me to improve.

Deliberate practice:

Import a 10 minute or so YouTube video with accurate human-made subtitles, or try one of the podcasts for learners shared by hellboy195.

It is important the timestamps are accurate so you can work in sentence mode. Now repeatedly play each segment (a-key) until you understand it, first while looking at the text, looking up words and using the translation function, later without looking. This might take 5-10 repetitions, or even more.

After finishing this video, let it sit for a while and try to (only) listen to the audio the next day, for example using the playlist; if you are happy with your comprehension - great, if not work on the critical passages again by repeatedly reading and listening. It's probably best to put this video and the following ones on some kind of rotation, e.g. first daily then weekly revisits.

I understand that this is a rather intensive process, but in my experience language learning is actually hard work. Repetition is key.

At one point you might notice that you actually start to know this video by heart, you could use this to your advantage and try start speaking or writing. For example by trying to repeat it, making slight changes as you go, or try to summarize it in your own words - but this orthogonal to listing practice just a nice by-product.

(Credits: I adapted this technique from https://hiv.net/ 's "Ear2Memory")