The attention of readers is drawn to a presentation of the principles of collecting and analyzing secondary data on the attitude towards Russia of public opinion in foreign countries, based on a generalization of the experience of similar studies. Each principle cited is illustrated by the example of a study of the attitude towards Russia of the Japanese.It is assumed that the methodology of secondary analysis should provide information that meets the following requirements: a) reliable and valid; b) with as unambiguous and clear interpretation as possible; c) having predictive value. To ensure this, it is necessary to take into account that 1) a meaningful interpretation of the dynamics of public opinion requires taking into account its historical state and, accordingly, a long analyzed period; 2) "attitude towards Russia" or any other country is a complex, heterogeneous and multidimensional latent variable, therefore, for secondary analysis, it is desirable to include as many empirical indicators as possible that have appeared in various mass surveys; 3) at the same time, the "attitude towards Russia" should be considered as a single variable, which is impossible without the reduction of a multitude of indicators, which is ensured, at least, by their homogeneity.The proposed conditions, applied to representative mass surveys, face the fact that their data usually have rigid restrictions both in the number of indicators and in the time coverage, which gives rise to the inevitable fragmentation of the data. Therefore, the collected information can, as a rule, be reduced primarily to some generalized "qualitative" assessments of the situation. These can then be formally combined into indices (for example, an index of favorability) for generalization and interpretation. At the level of indices, there are opportunities for partial and conditional filling of gaps in fragmented data.The application of the described principles and techniques to the public opinion of Japan made it possible to conclude that at the present time, the attitudes towards Russia in the public opinion of Japan are experiencing the deepest crisis in the entire post-Soviet history, and there are all the grounds to call the sentiments of Japanese public opinion clearly anti-Russian. Obtaining this conclusion did not require independent collection of empirical data, all the necessary survey results were already available in the public domain, their volume and quality allowed for an analysis that seems quite reliable and valid.