Sergej hosted me for 3 nights and it was amazing. He got me and my friend Pola from the train station, showed us a canteen with vegan food right away, trusted us fully with his flat and his cat, as he had a 2day fishing trip coming up, he drove us to the Blue Lakes of Kazan and took me to the Temple of All Religions on my last day in the city. He is a very kind and respectful person with good German skills and a beautiful apartment. I can only recommend staying with him. Thank you and all the best!