Intro
Begin the lesson by telling the same story twice, and having students find the difference.
(I personally told a story about my morning and sleeping in, but anything about you should work)
The first story, use no pronouns, and make sure to repeat your name many times. The second time, use pronouns as regular. They should probably get the difference.
Powerpoint
Move onto the powerpoint, and introduce pronouns for boys(him)/girls(her). I like to have students repeat the sentences, and then translate them into Japanese to make sure they understand the meaning.
Next, do the pronouns for groups (they) and objects (it). These won't be directly used in the guessing game, so they don't need as much focus. If you have time, translations are still useful.
On the sheet, students will make a "Pronouns card" with their name and pronouns. This is used in the game, later, but ultimately I just wanted a tiny bit of political correctness without the students even realizing it. Show the students your pronouns card, and have them make their own. Make sure they write their name with Romaji, as you'll need to read it for the activity.
Next, the students answer questions about themselves in the 3rd person on their sheet, using the same pronouns as their pronouns card. I found the best results come by taking the questions one at a time and checking around the classroom while the students work on each one.
Game
When the questions are completed, have the students hand their papers forwards to you. Shuffle them, and then read off the answers and have the students guess which of their classmates it is! This can be quite dramatic if played correctly. I personally like to have big suspenseful pauses and make game show noises if the students are right and wrong. Makes it a little more engaging, I think.
Note: There are two hidden slides on the powerpoint that are much more in depth with what each one of the pronouns does (subjective, objective, possessive) and a second batch of pronouns, (I, this, that) but I found that this was too difficult and too much information for the activity.