Disclaimer: you know it, I know it, the owners of RK know, it. That all rights belong to them, not me. Just borrowing the character, nothing else.
Dear Kenshin,
You are needed. Kaoru passed out yesterday during class. It was all so sudden. She was just walking through the students as they practiced their strikes, and I heard her weakly call my name. When I turned to see what she wanted, she began to fall, grasping at anything with her hands in efforts to stay up. She was burning when I picked her up. I have no idea how long she had this fever. Yutarou and Dr. Genzai examined her. As they did, I noticed that Kaoru had the same markings on her body as you did before you left. There were heavy bruises and lesions along her abdomen. Yutarou was able to verify for me that it is the same thing you have.
Dr. Genzai and he both agree that there is nothing that can really be done, except to make her comfortable. But they also warned me that if Kaoru is stressed, sad, overworked, or depressed, she could turn for the worse. In general, any disease can do their work faster if you help them by letting moods turn off your immune system.
That's why you have to come back now. If Kaoru continues to worry over you, she will die sooner than she should. I know she has amazing will power, and she will hang on as long as she can for you, but things will only get worse from here on out.
I have sent for Megumi-san to come quickly. She would never let Kaoru give up on her life. That's the way they are. Megumi can talk sense into Kaoru. Sanosuke is also coming to find you. I don't know where he will look, but he is determined to find you.
For now, I am taking care of Kaoru and sleeping at the dojo again. Tsubame is helping, she has also agreed to stay at the dojo for a few nights. Once Megumi arrives I plan to go get Kenji myself. He needs to be with his mother. Just like you need to be with your wife.
"Sanosuke! Matte! Wait, don't leave yet." Yahiko was running through the gate of the Kamiya dojo, chasing after a rooster head that was making his way towards the river.
Sanosuke turned and waited for the boy to reach him. "Hey, you can't come Yahiko. You need to stay here and take care of Jou-chan and the dojo."
Yahiko finally reached him, "I know I know. That's not why I came. Here." He shoved a stack of folded papers tied together with one of Kaoru's hair ribbons into the older man's pack.
Sanosuke gave him a questioning look. "They are letters to Kenshin." Yahiko explained. "They tell him what has been going on here. Make sure he reads them, especially if he is reluctant to come home." Sano gave an affirming nod. "Find him Sanosuke."
"I will Yahiko. I will."