The string you provided ("%D1%85%D0%B5%D0%BD%D1%82%D0%B0%D0%B9 shinseki no ko to o tomari dakara") mixes percent-encoded Cyrillic (which decodes to "хентай") and Japanese romaji ("shinseki no ko to o tomari dakara"). That appears to refer to "hentai" plus Japanese text meaning roughly "because I'm staying/rooming with a relative's child" (親戚の子とを泊まりだから — grammatically off but likely intended).
Whether you're a fan of Japanese media or simply looking for a story that will warm your heart, "%D1%85%D0%B5%D0%BD%D1%82%D0%B0%D0%B9 shinseki no ko to o tomari dakara" is a tale that is sure to leave a lasting impression. Whether you're a fan of Japanese media or
%D1%85%D0%B5%D0%BD%D1%82%D0%B0%D0%B9 decodes to "хентай" – the Russian transliteration of "Hentai" (perverted/anime pornography).shinseki no ko to o tomari dakara is Japanese Romaji that roughly means: "Because it's staying over with my relative's child / I'm staying over because of my relative's child..."