An information processing system characterized by: an information processing apparatus; and a terminal apparatus comprising: a notification section configured to notify the information processing apparatus of a learning data set, wherein the learning data set includes input time-series data associated with a first feature information, to which a label is assigned, and a second feature information, to which no label is assigned; and an acquisition section configured to acquire, from the information processing apparatus, generated time-series speech data having features indicated by the first feature information and the second feature information, wherein the information processing apparatus comprises: an acquisition section configured to acquire the learning data set from the terminal apparatus; an identification section configured to identify the first feature information from the input time-series data with a neural network; an inference section configured to infer the second feature information from the input time-series data and the first feature information with the neural network; a learning section configured to learn a parameter of the neural network; and a generation section configured to generate the generated time-series data having features indicated by the first feature information and the second feature information, the first feature information and the second feature information being acquired by the acquisition section, wherein the generation section is configured to generate the generated time-series speech data with the neural network; wherein the input time-series data are user speech data, and the first feature information and the second feature information are information indicating features of the speech data, and wherein the information processing apparatus and the terminal apparatus are connected by a network. an information processing apparatus; and a terminal apparatus comprising: a notification section configured to notify the information processing apparatus of a learning data set, wherein the learning data set includes input time-series data associated with a first feature information, to which a label is assigned, and a second feature information, to which no label is assigned; and an acquisition section configured to acquire, from the information processing apparatus, generated time-series speech data having features indicated by the first feature information and the second feature information, wherein a notification section configured to notify the information processing apparatus of a learning data set, wherein the learning data set includes input time-series data associated with a first feature information, to which a label is assigned, and a second feature information, to which no label is assigned; and an acquisition section configured to acquire, from the information processing apparatus, generated time-series speech data having features indicated by the first feature information and the second feature information, wherein the information processing apparatus comprises: an acquisition section configured to acquire the learning data set from the terminal apparatus; an identification section configured to identify the first feature information from the input time-series data with a neural network; an inference section configured to infer the second feature information from the input time-series data and the first feature information with the neural network; a learning section configured to learn a parameter of the neural network; and a generation section configured to generate the generated time-series data having features indicated by the first feature information and the second feature information, the first feature information and the second feature information being acquired by the acquisition section, wherein the generation section is configured to generate the generated time-series speech data with the neural network; an acquisition section configured to acquire the learning data set from the terminal apparatus; an identification section configured to identify the first feature information from the input time-series data with a neural network; an inference section configured to infer the second feature information from the input time-series data and the first feature information with the neural network; a learning section configured to learn a parameter of the neural network; and a generation section configured to generate the generated time-series data having features indicated by the first feature information and the second feature information, the first feature information and the second feature information being acquired by the acquisition section, wherein the generation section is configured to generate the generated time-series speech data with the neural network; wherein the input time-series data are user speech data, and the first feature information and the second feature information are information indicating features of the speech data, and wherein the information processing apparatus and the terminal apparatus are connected by a network.