If you are an Android user, you might have remembered the anime app Wake Me Up, Asuna. That app allowed fans to talk to Asuna and she responds back at you whether you are speaking English or Japanese. She would wake up if your phone was on as an alarm and she will always hi to you. She was also voiced by the same voice actress in the anime (only the Japanese voice actress). Unfortunately, this app later discontinued in January 15th, 2019.
Now, looks like Asuna has some competition in the app world. Once was an an exclusive Japanese app, there is an English app where you can have the explosive mage girl Megumin from Konosuba in your phone. According to Crunchyroll, there is an app called Isekai where you can talk to the characters and have them respond and perform functions like doing a timer and alarm. Currently, Isekai will allow fans to talk to Megumin. The app has just released an English pack DLC where she will respond back to you and understand you in English. The voice actress is still the same person, Rie Takahashi.
The English pack is around $7 and this will allow her to speak in English text and hear you in English. The app will be for Android AND Apple users.
Sorry Asuna, as much as I love having you in my phone, I have to move. Are you excited to have Megumin in your phone?
Matt-in-the-Hat 
Beware, this app is malware. I installed it on my device and it exploded.
Yikes! I thought Samsung fixed the whole exploding phone dilemma. Everyone is going to need a new phone lol.