I think it was great.
The animation was great considering it's only your second flash animation. The backgrounds were really great. You have a unique style, and the parts where he had flash backs was a cool concept. The voice acting wss pretty good, and the sound effects made it more realistic. Choice of music, despite the fact that people know where it's from, if the song befits your animation, so use it.
In terms of the Japanese language being added It's good as long as it makes sense to the story and is used correctly.
Here's a few suggestions to change:
1.) Dual Arms is spelt incorrectly. You were pretty close though. They translate Dual, as [Dyuaru.] The Dyu is short. (Katakana De, with a Katakana small yu.) And Arms as [Aamuzu], so just change the su into a Zu. The Japanese tend to translate s sounds on the end of words as a z sound.
2.)If you needed some Japanese for the resevoir scene ask someone that knows what you wanna say, instead of making it up. Because that was pretty funny for me to see, unless you intended it that way.
If you need help in translation, message me and I can help you.