I teach pronunciation and have experience with Japanese students. Japanese has 19 sounds, but English has 44. Also, Japanese doesn't allow consonant after vowels. So, accurately pronouncing English takes significant training for a Japanese speaker.
If you have a strong Japanese accent, this is what the person heard.
fu > hu, ur > ah
future >> hutah
ae vowel > ah, hard to hear final N, extra vowel U at the end
and >> ah-du
er > ah, l > r-like sound, extra vowel U at the end
eternal >> ee-tah-nah-ru