Hello, my name is Masao Ikuo. Thank you for your patience, we are pleased to present the fourth volume of the detective Ryousuke Kibukawa incident story, ``Crimson Feathers on the White Heron'' . Do you all remember the meaningful words that Shirasagisu Ituna said during the Kairoukan Incident? This time, I would like to introduce a sad and heartbreaking incident that she encountered in the past. Nowadays, with her excellent insight, deductive powers, and outstanding personality, she is active as a detective assistant, but what happened in her past? Why did she decide to become a detective? They will be revealed at the end of the story. Also, when configuring it as an app this time, we added a little trick. Suffice it to say... I, 生王は, will not appear in the main story this time. So, from whose perspective does the story progress? That will be the key this time. The story begins with a shocking fact that she reveals in the prologue. Please enjoy ``Crimson Feathers on the White Heron''.