User blog comment:B214/High School DxD EX/@comment-50.139.232.230-20160202070950/@comment-93.105.246.116-20160208222553

Have no fear he is stated to have a human form however he did not stay for any chit-chat so he left in the same state he appeared in. Plus knowing Issei he would rather lose his powers than turn into a huge dragon permanently which would mean he can't have sex anymore. Also this might be a form he will use in Volume 21 when he fights 666 - he is suppose to meet Great Red again along with Ophis and Lilith so he may get some new power-ups from them.