a couple of reasons, been watching jap news almost every day since he went into power

1. too many gaijins masuk
2. rice shortages and too expensive
3. tourism is out of control especially in kyoto a lot of ppl want him to do smtg to curb the people
4. money scandal
5. 2024 noto earthquake hes not doing much to help, many ppl complaint he rather donate money overseas to help palestine and other countries than his own
6. trade deal with trump not that good especially to japan automotive industry, a lot of jap ppl disagree with what he deal with the us
7. rising living costs, apa rancao also up price. true story when im in tokyo april most of the restaurants post due to rising living costs they have no choice but to increase the price of food and beverages
8. he like to have good diplomatic relations with china & sk but most jap ppl disagree
9. weak yen, high consumption tax

and so on..

but now doesnt matter who do pm, takaichi or koizumi everyone also dont like lol

tldr: japan is doomed