I would generally recommend Pimsleur, but knowing the hiragana and katakana would be the equivalent of knowing the alphabets. It depends what your goal is.

Then, honestly, look nowhere else but Pimsleur. If I'm not mistaken, you can do the first lesson for free to have a preview of how you can benefit from the entire course. In the older versions, they usually give you a short conversation in the language that you want to learn. They all sound gibberish to you, but at the end of the 30 minutes, voila! You can suddenly not only understand the conversation, but you can also reply in kind. I used their courses to speak French, German, Hungarian and Japanese. Of course, Pimsleur alone will not carry you to have a conversation because you will need vocabs but Pimsleur is the best way to structure your way of thinking to be like a local by slowly teaching you the grammar organically. For vocab, as a kickstarter, there is WaniKani (after you master the hiragana and katakana). It uses the same principle of SRS (Spaced Repetition System) to help you remember things in a long term. Beware, though, because many people there will advise you on jumping to grammar on the get-go, but I have failed tremendously bad at speaking German when I did it in a conventional way like this (and I studied it for 4 years, while I only took a Pimsleur German course for a shorter time and I could immediately ask people for directions and understand what they are saying). I am not doing this because I want to make profits out of Pimsleur, but I just want to help people out with the best way to learn a language in order to speak it, listen to it, using it to communicate rather than to just be able to read sentences and then calibrating its meaning in your head according to grammatical rules slowly. That is good for reading and writing, but not for communicating like when you want to have a chat with someone.

My goal is to be able to speak with someone and having minimal problems with understanding and answering back...

Start with learning hiragana and katakana! They're quick to learn, and once you have those down you can write anything.